Wired or Wireless bike computer?
I've only ever used wired computers because they seemed more reliable. However, I have a friend who uses a wireless computer.

The biggest problem I've observed is that when he starts riding after a rest he has to make sure he 'wakes up' his computer otherwise it won't track the ride until he does. He's forgotten (and lost ride data) often enough that this is a big dealbreaker for me.