So far for me, M120 has been very stable. It definitely resolves some small but annoying issues. For example, it resolves an error you frequently get in M100 that says Creo cannot exit due to operations being performed on the background. It doesn't pop up all the time but when it does you're forced to kill Creo from the Windows Task Manager. This is gone in M120. It's too soon to say if this build is any faster than M100. M110 was notoriously slow according to the OCUS benchmarks.
If you're in M090 or lower, I'd consider moving up to M120.
However, I disagree pretty strongly that going to Creo 3 is a good idea. There's no way I'd move my production environment to a F000 level release. I don't care if that release claims to walk on water, there's no way it's ready for prime time.
This sounds like I'm saying I don't trust PTC to put out a product that's been sufficiently tested and vetted for everyday use. If it doesn't sound like that, then let me make it crystal clear... I Do Not Trust PTC To Put Out A Fully Tested and Acceptably Bug Free Product on the first release. If you're running without Windchill and you're a very small business with only a few seats, you can probably safely move. If that's not you, then I'd advise testing the heck out of Creo 3 and waiting until at least M020 before moving. Even that is really aggressive. Some features of Creo 3 won't even be released until M020. Unless you want to be promoted to chief bug tester and overall chump, I'd be very careful about jumping too soon.
My goal is to move my production environment to Creo 3 in either late Q4 of this year or Q1 of 2015. That depends quite a bit on testing, benchmarks, and the impressions of the few brave (or insane) souls who take the plunge early. Don't get me wrong, I like Creo 3 and I'm excited for it to mature a bit into a product I can deploy... But over 25 years of experience deploying Pro/E and Creo tells me to be smart and wait until the big showstopper bugs have been found and fixed.
I'm still working through bugs from Creo 2, fat chance I'm doubling down on Creo 3 and hoping for a miracle.
