For the money, it is satisfactory. I was not willing to spend more than 150€ on a bike.
It is assembled very easily.
It does its job perfectly.
Satisfactory resistances. I haven't even put it on full.
The only negative is the saddle. It is the most uncomfortable thing. I couldn't sit on it for more than 5 minutes. It hurts the buttocks. Fortunately, the problem was easily solved by buying a softer saddle, made of foam material, from sh#in, worth 10€. It would be preferable to put a better saddle, rather than a useless water bottle, included in the package. (The photo shows the new saddle I bought, not the original one.)
It makes a little noise, you can hear it, but it is not annoying.
It is stable. Pretty nice, I must say, in terms of appearance.
I am 1.73 and the height of the saddle is ok for me.
So far, I am satisfied. I have not identified any other negatives.

For the money it costs, I would say it does its job quite well.
Assembly: easy. It can be done in 20-30 minutes with your own pace. The tools you need are included in the package (2 German wrenches and an Allen screwdriver). You don't need anything else. Nothing was missing.
Design: interesting. It is suitable for all fitness levels. Attention: Very overweight people may not find it comfortable. If you want to maintain a good physical condition, or simply lose some weight (always in combination with a proper diet), it is not a bad choice. If you are particularly bulky, it is unlikely to suit you. The saddle and handlebars can be adjusted in height. The position is a bit hunched if you hold the handlebars with your hands. I didn't find it so comfortable, but of course you can ride without holding the handlebars, which are not adjustable in angle, but with a small modification and a set of longer screws, you can bring them further back.
Material quality: simply good.
It is well balanced and has adjusters on the legs to balance it if the floor is not perfectly level. At least until the wheel brake settles a bit, there is a slight uncertainty in the stability of the resistance rotation (which is completely mechanical), but nothing significant. It only has 5 plastic parts in secondary areas. Its construction is all-metal and appears to be durable for normal use.
The accompanying computer shows time, calories, odometer, and speed, but in terms of accuracy, I don't think it is precise, like almost all of this type available on the market. However, it does its job indicatively. It is simple, not adjustable, operates with two AAA batteries included in the package, and works with a motion sensor on the wheel, so when you stop, the measurements freeze. As soon as you start pedaling again, the measurement continues. The indicators work cyclically. If you want to see a specific one, you simply press the only button it has. Resetting the indicators is done by holding down the button.
The saddle is not just plastic, but has foam and spring suspensions. Nevertheless, it is not comfortable. For a bulky person, a change will definitely be needed.
There are no vibrations or shakes during rotation, and its overall function is positive. The rolling friction, as it comes from the factory, is very good.
It has a base for placing a mobile or tablet, and a pouch with a small water bottle, where you can of course put a small water bottle.
The pedals have grips for retention and are made of metal and serrated.
Efficiency: it definitely does its job without any serious issues.
Should I buy it?
If you don't have more money for something of higher quality but still want to get your job done now... it's not bad.
As for its durability over time, I cannot answer yet. I imagine that with normal use, it will last for some time. We shall see.