I just recently installed this unit and so far I'm very happy with it. It is running on 2.something firmware.
The one thing I've noticed has been occasionally the gps will go a little crazy. I was driving down the highway and all of a sudden I noticed my icon was spinning around randomly and my speed was all over the place. I was travelling at about 120km/h but it was reading anywhere between 105 and nearly 400km/h. 
It was a pretty clear day and I had the gps antenna on the roof so it should have been receiving a good signal.
Anyone have any ideas what could cause this?