GB breaks the droid x's accelerometer and compass. It was noticed immediately after the first leak, and has been present in every build so far.
I only know what I read in other forums, but someone somewhere had mentioned that this area of the code has been reworked for GB.
I was part of Moto's SOAK and I tried and tried to get Moto's attention on this -- and they completely ignore the problem, and will not acknowledge there is anything wrong here.
The only thing they would mention was the problem in Google Maps and that upgrading to the latest version of Google Maps fixes the problem (the one they won't acknowledge). The Google Maps update makes Google Maps work better, but does not at all "fix" the problem.
To me, Motorola's decision to ignore this problem is the worst possible situation. I paid 200 bucks for this phone in August 2010. And I'm locked into a 2 yr contract that I've already shelled out about 1,400 bucks on during my first year, and I've got another 1,400 bucks to pay for another year of my contract.
I wouldn't even care if they fix it or can't --- It would have made a world of difference to me if they would just acknowledge there IS a problem.
What makes it even more difficult is that many people will run google sky maps and see that it does "run" on the phone. It doesn't FC or lock up the phone, and if you're not really paying attention to what's on the screen, it "appears" to be working. When someone tries to post about the problem, someone always wants to chime in and say "it's working perfect on my droid x!" becuase they "think" it is working right.
So, GB cripples the droid x - by breaking the accelerometer and compass - and the solution seems to be to sweep the problem under a rug and pretend there is no problem.