I've been pretty lucky with my eris. The only real problem I've ever had with it is indeed the trackball, but not the common one. It rarely, if ever, scrolls down when I want it to. Sometimes it will work briefly after the paper cleaning trick, but it quickly goes back to no response after that. I'm looking to upgrade, but as of right now I'm kind of waiting on an announcement for the Incredible HD.
I'm going to live forever, or die trying.