To be honest, before blaming WP as a whole, people should first look at their own set-up and try to identify if it’s something at their end first, eg. plugins.
I concur. The fact that some people have upgraded perfectly well shows the upgrade itself is fine; if it was buggered, everybody would be affected, no?? I’ve now upgraded a total of 4 2.7 blogs to 2.8, some large, some small, all are fine.