The first leaked Ice Cream Sandwich build for the DROID 4 has been acquired straight from Motorola. Since the DROID 4 was on the list to (eventually) get the ICS update, this was expected. This is still an early build, so don’t expect too much stability.
Upgrading the DROID 4 is always a risk, thanks to Motorola’s stance on hacking. Besides the obvious fact that you won’t be getting official updates when on a leaked build, you might not even be able to revert back to Gingerbread. Even trying to get back to Gingerbread could brick your phone. Thanks, Motorola, for not even providing the tools to fix our phones. So do this at your own risk.
Watching Motorola’s progress with ICS, I’m afraid it may take a long time to get it officially. Leaks are even slow to emerge. So let’s hope something changes and ICS will be officially released sometime this year.