I play a little. Diatonic - never tried a chromatic, but think it would be fun to try. diatonics pretty much play themselves, if you are looking for a pretty simple part. I never quite understood how Alanis Morrisette could play such an easy instrument so poorly.
It takes a bit of practice to dial in bends and flutters, and use your tongue and whatnot. I just recently spent far too long recording a harp part to a recording of Arkansas Traveller - probably one of the tougher songs I can play. It's tough at least to play fast.
I got a book that came with a CD (actually might have been a tape - I got it a long time ago), and would recommend the same. you'll get it down in no time.