I've read a number of the negative reviews and don't get where they are coming from. Maybe the few games they have installed don't have a huge impact but for someone like myself that has 50+ games installed at a time, this is the result:
Total App Space: 913.80 GB
Space Saved: 191.62 GB
Compressed Apps Space: 722.19 GB

Yes, not every game can be compressed by a large amount ( for example, Everspace 2 only compressed .01 GB and Oblivion Remastered only compressed 2 GB)
But a good chunk of games seem to compress 10-35% (for example, Baldur's Gate 3 compressed 18 GB and Skyrim SE compressed almost 60 GB.

I noticed absolutely no difference in game performance between compressed and uncompressed games. I also have not seen any issues caused by compression in any of the 50+ games I have compressed.

All in all, $7 to save 200 GB of space on my PC is well worth it.

Regardless of the controversy some people have stirred up over this app, it works - and works well. I recovered over half a TB back. Didn't have to futz around, the graphical interface was fine. Worth the price just for that.

My only request for the devs would be that it would be handy to see the drive a game is installed on while choosing games to compress.