This has got to be one of the coolest plugins out there especially if you're into beat chopping and manipulation. Before this, I was confined to using Recycle (which is still a sweet program) and having to dump the samples manually into Fruity Loops. With Phatmatik Pro I can audition, chop, and manipulate the loops and whatnot right within FL and it's priceless for catching something on the fly before the inspiration leaves ya.
Of course Phatmatik can be used on samples other than drum loops but that's primarily what I use it on so thats where my bias may lay. The only comparison to this VSTi is the self-contained Fruity Slicer (from Fruity Loops) and possibly Bomb That Beat. The main difference is that this program is so close to Recycle that if you've used it before, you'll have no problem migrating to Phatmatik Pro. And as far as stability, I have never once had an issue to date (knocks on wood).
All and all this is must have plugin especially for y'all drum choppers out there.