I bought mine December 2010... my stick started acting up a good few months later, and after a few tests, it was confirmed that the stick base was broken. I had to send it back (base only) and got a replacement one less than 2 weeks IIRC. Can't exactly recall now. But aside from that, had absolutely no problems at all. Worked in DCS A10C straight away, and to be honest, I've had more "trouble" getting it to work seamlessly with Falcon 4 BMS and FSX.
A few other users have had various problems as well with either the throttle assembly or some buttons not working and most send the throttle back and get a new one or TM ships them a new part.
I would consider these teething pains on a new product, but given the hassle-free use and accuracy of the Warthog, it is annoying when it hits you but then 98% of the time, "it simply works." With limited game time, knowing I can simply sit down, fire up my profile, load my game, and go fly with my TM Warthog, it is well worth the money IMHO.
The only thing I do for my WH is to cover it when not in use, keep the dust away. I've never opened up the stick/base or throttle to change anything.