IMPORTANT READ BEFORE YOU BUY THIS APP

I know personally that polarpaul and crabjuice (two reviewers who have this app 5 stars) work for sonosaurus (the company that made this app) and I suspect many of the other good reviews are planted as well. That being said, i speak as someone who has actually paid money for this app and want you to know that it is falsely advertised.
There are several instruments and many of them sound good, but if you come on expecting to actually record loops or make any beats or do anything beyond just playing the same scales on a collection of instruments, look elsewhere.
The recording and loop creation works well while making the song, but after you save it and come back, the app plays each looped instrument from the beginning instead of where you started recording it, effectively ruining your song.

Ratchetmaster42069 about ThumbJam, v2.3