I've had the Motorola Milestone (the Canadian take on the 'Droid') for a few months now having migrated from my HTC Touch Diamond (CDMA). I've used several Motorola phones in the past - some good (V3, Q9c) and a few not so great (V9, KRZR) so it was a little bit of a gamble (although it is not often that a flagship product is tragically flawed). The switch to the Milestone represents not only a change in hardware but an entire shift in paradigm. You see, the Milestone is powered by Google's Android operating system.
With my only other smartphone exposure being Windows Mobile based, I didn't quite know what to expect . In fact, I was kind of worried -- I had just started dabbling with little development projects with Windows Mobile. While I've not had the opportunity to start developing for Android, my experience so far suggests that it won't be a painful learning curve. In short: I'm (very) impressed.