I have changed many printers, scanners, etc. for my office (professional space). I can easily say that it is the best I have ever bought. I have had it since 08/2018 and it works tirelessly (scanning-printing in A4 and A3). The automatic feeder is very convenient (it only takes up to A4) for scanning-copies, where you can scan double-sided without having to turn the pages (it takes about 15-20 sheets). The glass surface is also very useful (it takes A3 as well - double-sided does not work). A few days ago, I bought a second one. I looked at the invoice of the first one and I bought it for €200 in 2018, and the second one a few days ago for €279. There is nothing similar in the market (at least in HP, which I am looking at). Until a few months ago, it was available in 1-2 stores for prices of €350 and above, and with availability in 30+ days. Now, it is available and you can find it for €250-260. The original cartridges of the PRINTER... I (still) use those (with pain) and with the usage I do, I change them about 7-8 times a year... For offices like accounting, law, etc., it is unbeatable (maybe even for engineers - I don't know).

Top machine, real tool. It has solved my hands mainly in the scanning field. And even if it wasn't a printer, which is also very good in this field, it is worth every last euro just for its scanning capabilities.

Capabilities: 1) Scans from the automatic document feeder (ADF) up to 35 sheets of A4 FRONT-BACK in one pass. It automatically writes it to the hard drive in a PDF or separate jpg images and can send it directly to email if you want. Some talk about skewed scans from the automatic feeder. I have scanned hundreds of A4s and have not noticed anything like that, not at all. Maybe these specific users have not enabled automatic alignment in the options or I was just very lucky with my purchase.
2) Scans in A3+ size on the flatbed scanner (glass). This alone places it in a very special category of multifunction devices. Personally, I don't know any other A3+ scanner priced below 600-800 euros. This size allows you to easily scan open books. I have scanned an 800-page book in two hours using this method. Again, it automatically saves it to pdf, jpg, sends it via email, etc.
3) Prints in A4 and A3 (!!) color automatically front-back (full duplex)
4) Obviously, it produces color or black and white photocopies and also functions as a fax for anyone who still needs such a thing.
The touch screen is functional and beautiful, it contains all the basic functions.
All of the above for 230 euros with cashback from HP, so essentially it costs 200 euros.
I love it so much that I thought about getting 2 machines, purely for home use!

With the purchase of dedicated flatbed scanners constantly shrinking, multifunction devices like this one are the way to go in my opinion, simply for scanning.

Excellent!
It prints and scans A4 and A3.
It scans multiple A4 sheets at once from the automatic feeder, front and back, in a single pass and automatically saves them as a PDF file or separate JPG files on the computer.
For A3 scanning, it can only scan one sheet at a time from the glass.
The ink cartridges are a bit expensive, but thankfully there are compatible ones available.
It has two paper trays, allowing you to have both A4 and A3 paper at the same time and automatically select the print size while printing, without having to change paper and size in the tray each time (like in the 7720 model).
The WiFi works great and fast, it prints instantly even with large files, and there are no disconnects.
In its price category, it may be the best machine in its class, and there is also a €30 cash back program from HP with every purchase of this printer!
One downside that I don't like at all is that when the bottom tray has A3 paper inside, it doesn't close completely but protrudes 8 centimeters outward. Besides looking bad, dust also gets inside the paper. This problem can be solved with a dust cover for the entire printer, which will also protect the exposed scanner mechanism on the top.
It goes without saying that it is larger than traditional all-in-one printers and will require the appropriate space (roughly 55x58cm in size).

Update 12/2022: The printer works great, everything is perfect, but I should mention that I bought it when it cost €169 (€199 store price minus the €30 HP subsidy), and now I see that it costs almost €340!!
I think at this price, it is no longer the best machine in its category. It's worth doing some more research before purchasing

It is a very good printer. There is nothing better at its price. Everything is automatic. It scans A3 and slightly larger than A3. It prints A3. Its construction is mostly plastic but of good quality. It connected immediately with USB and WiFi. It is good for engineers who need A3 drawings. I have not encountered any problems with printing. It is not fast but it is reliable. The ink cartridges (original set of 4) cost around 120 euros (2020 prices). I use ink cartridges from Germany. In foreign countries, you will find 2 companies from Germany that have the 953XL ink cartridges. Look at the photos. The ink cartridges last for 2 years. Store them in a dark place in their packaging if you buy multiple sets. Both companies are good and provide warranty for their ink cartridges. The set of 8 ink cartridges costs around 60 euros with shipping. One set (4 ink cartridges) prints from 1300 to 1800 A4 pages. I bought it for 200 euros minus 30 euros refund from HP, so 170 euros. So far, it has printed over 6000 A4 pages (12 months). If you find it, get it, it's a good opportunity. Always use imitation ink cartridges and you'll be fine. Now there are ink cartridges in Greece at reasonable prices.
WARNING. NEVER UPDATE THE FIRMWARE. IT WILL NOT ALLOW YOU TO USE COMPATIBLE INK CARTRIDGES.

Amazing machine. I print several pages daily for about two years now and it hasn't presented any issues. Perhaps the best choice I could have made.

5/22/2021: I am adding my opinion after 3 years of use. I bought the printer on 6/2018 for around 260 euros, its performance was flawless, but on 3/2021 it suddenly stopped recognizing the ink (genuine). It recognizes that they are genuine and displays the ink levels, but constantly gives a message to change the cartridges and doesn't print but scans instead. I contacted HP, but after 45 minutes of phone guidance, the problem was not solved. Then I took the machine to the official representative for service (out of warranty), but even there I didn't receive a clear answer and they didn't repair the printer. However, while talking to the people from the official service and the three HP services in Attica, they informed me that the injekt all-in-one machines are not repaired, either because spare parts are not imported or because their repair is not cost-effective. Then I tried to install other genuine inks, but again the same message appeared. It is disappointing that such a big company doesn't have the ability to repair injekt printers and at the same time doesn't inform about this limitation at the time of purchase. However, because the 7740 is a POWERHOUSE and because we love HP, as all our computers and printers have always been HP, I proceeded to buy the same machine again on 5/2021...!!!

I have had the printer for about a year. I bought it mainly for A3 printing and scanning. It is a very good machine for printing, with excellent quality, fast response, and easy installation. It works perfectly with wireless connection (wifi) on all computers, tablets, and mobile devices. The automatic double-sided printing is very convenient. Indeed, the machine is bulky and the A3 paper tray does not close completely, but you get used to it.

The only negative aspect is the scanning from the document feeder (ADF), which produces skewed results when scanning multiple pages front and back (e.g. a contract). I contacted HP, thinking that the product was defective, and after some "fixes" such as alignment, software upgrades, etc., the problem persisted, so I requested a replacement with a new product. Unfortunately, the second product had the same issue. I was informed that they couldn't do anything more.

It's a shame for HP and for such a feature-rich machine that otherwise works exceptionally well to have this unfixable flaw.

I recommend it to someone whose need is more for A3 printing and not so much for multiple scans.

I have had it for over 6 months now.
It replaced 2 machines, a Canon Pixma MX435 A4 all-in-one printer and an Epson 1280 A3 printer, which could not be stacked on top of each other.
It is indeed relatively bulky but compensates with its speed, print quality, ease of installation, and networking and remote printing capabilities. In cases where I received a PDF on my mobile and sent it to be printed via Wi-Fi, I did not encounter any problems and it honestly saved me a lot of trouble.
It is indeed annoying that the bottom drawer where I put the A3 paper needs to remain open by about 10cm, but it is a matter of habit.
It is excellent for scanning and copying, fast and high-quality.
In case of any issues, I have downloaded the HP Print and Scan Doctor, which solves 95% of the problems or suggests solutions.
23/11/2020
The cost of original ink cartridges unfortunately makes it uneconomical as time goes by. We are in a dilemma whether we should look for non-HP ink cartridges. Unfortunately, the mostly poor quality of aftermarket ink cartridges does not help with the endeavor. But 106 euros for a set of XL cartridges is a bite. Buying an EPSON Ecotank is probably a more cost-effective option.
10/04/2022
We found refurbished ink cartridges of very good quality (Mediarange) and managed to reduce the printing cost without compromising much on quality.
I add 1 star because it continues to work flawlessly for 3 years now.
You don't often come across this in a home printer.
29/08/2023
Attention! Disable automatic updates both from the printer and from the application that loads with the printer's drivers. The latest updates disable the recognition of genuine (!!!!!) ink cartridges from previous batches. It may not recognize genuine ink when installed, label it as older technology, and completely disable printing.

The last HP I bought was before 2000 (a faulty model), and since then I have bought 10+ Epson printers, most of which I destroyed because I used bulk inks, while when I used genuine inks, they didn't have any issues, so I might be biased against HP. It was purchased solely to print some designs on A3 paper and scan books. The impressions are from the first day of use.

In the positives:
• The flatbed scanner is A3 and is the only reason I bought it, because almost all A3 printers at this price range had A4 scanners.
• The inks are probably Pigment and they don't smudge with water like the colored ones from Epson with continuous flow.
• Small touchscreen but good.
• It has options to print remotely, but it's only for cases when you have someone near the printer who can't print from a computer...

In the negatives:
• Scanning from the auto feeder is for A4 pages lengthwise and not widthwise for A4 to also fit A3.
• The printheads are integrated like in an Epson, and I bought this printer thinking that each time I change the inks, I would also change the printheads.... So the inks are very expensive for multiple uses, and I don't think they sell bulk inks at cheap prices.
• The scanning menu is simplistic and has nothing to do with Epson where you can do wonders.
• It requires a huge space.
• When you put A3 paper in the tray, the lid doesn't close properly and it protrudes...
• You have to immediately spend 95 euros for the inks because the inks it comes with are trial ones....
• I didn't consider that when scanning a book, the two pages don't come out exactly straight and it requires special software to make corrections.
• The OCR it has doesn't satisfy me compared to Fujitsu ScanSnap