For occasional and light use, it is effective, practical (because of its shape), and economical. For frequent and/or professional use, it definitely does not do the job.

I would rather suggest you go for something around 4-5€ that can be used because pretty much all the sponges I have tried close to 1€ were not worth it and break easily. It is much more worthwhile to go for a hand pad with replaceable sandpaper

Good price but unfortunately they don't last very long. Especially the Coarse one, many particles come off during the first use and it makes a mess.

Economical and effortless. Perfect for the hobbyist. If they get clogged from use, just give them a little tap to remove the dust and they work again until they wear out.

Good and user-friendly.
I don't have experience with other sandpapers on a sponge to compare brands, however, it seemed more convenient and durable than almost all the equivalent sandpapers on sheets that I have used.
It puts much less strain on the tendons, etc. during movement and the work is done faster.
I don't know to what extent it is convenient for details and very small surfaces. On the large rough wooden table that I used it on, it was perfect.
I recommend using gloves because, no matter how you hold it, your fingers/palm are in contact with a rough surface.

In order not to make a mistake, according to the supplier, the Coarse - Medium - Fine correspond approximately to numbers 30 - 60 - 100. This particular product is rigid and this should definitely be taken into consideration depending on the task one wants to accomplish. (There are other products that are absolutely flexible and very durable nonetheless.)