no real problems so far other than very occasionally the unit will stop playing a cd for no reason. It only seems to do it on really warm days though so might just be it's getting a bit hot and cutting out to save itself. Used the sat nav to guide me a few weeks ago and was really impressed by it! Sorted out routes nice and quickly, gave plenty of warnings and re-calculated quickly too.
Radio signal seems to be the only problem, doesn't seem to search for signal when it looses it, just makes white noise and you have to adjust manually but doesn't really bother me as i only really listen to cd's anyway.