About as good as you could want it to be. Sounds cool and has a nice, simple but flexible interface and uses up very little CPU. The main downside for me is that this synth is a little too much inclined towards the whole, crazy, in your face, digital drums spectrum which means you end up with some cool sounding drum parts that don't really fit in with anything else, that always seem to be saying "hey look at me!" rather than just providing a rhythm track. I want to like this more but realistically i don't think it's quite as use-able as a more basic sounding synth like ERS Drums.
This drum machine is pure analog and it sounds funky i love it, hard to believe this is free, I am a big fan of analog drum machines and have been looking for this particular sound on the computer, it has that mechanical low-fi very dirty sound. Also the sound shaping is awesome.