Re: One experience - some good some bad
Advice is to leave the servers alone up until a couple of weeks/month after release, they tend to iron out all these issues in ~2 weeks after release.
In my case I always upgrade servers once the x.1 is released, I do it for everything Centos, RH, Debian and of course Ubuntu.
Upgrading on the first couple of weeks is always risky no matter the Distro, upon release they are more concerned from getting it out of the door on time than anything else, so they focus on the installation issues for launch and the upgrade issues they work it on later once people begin reporting issues.