The engine is harder to service because its rotary, but other than that I haven't heard of any major problems. You should also check Mazda's site and see if they had made any part recalls on the car.
I know of CorkSport and the MazdaSpeed but I can't find any others. I'm trying to tune my 2010 Mazda3 hatch and not many generic companies, such as K&N and Magnaflow, have designed parts for it yet.