I've had my Ambit for about 2 months now and am very happy with it so far. There are a few bits that need sorting when they update the firmware like adding the ability to create an interval session workout, but nothing that would make me swap it. In terms of functionality its great.
I had a Garmin before I got my Ambit, in my opinion it looks a lot better than the Garmins, has better battery life and is a better all round training device.