The only problems I have had with CoPilot are:
It takes forever to set up initially. The downloads are understandably huge (great maps, I'm just impatient at times) and no download "counter", so plan ahead. Don't try to install it when you need it.
The program is (again understandably) shockingly loud when sitting in your living room. I say understandably, because it's meant to be used while driving/walking/whatever outside. If you do get the App, be ready for that little shock
Great program, though. Works just fine on my Eris
Actually, afte reading this, I need to specify - These are not problems. These are things new users need to be aware of. The program has to have large downloads, it's downloading entire maps of a region including POIs. I just wish tere was an indicator of how it was going.
And the default volume level is intended to be heard over road noise and such. It was just a bit of a suprise, sitting on the couch watching TV. Got me one of them looks from The Missus, too...