When Windows 95 was released it had over something like 50,000 (or possible 500,000 - I forget) errors in it. That wasn't even a BETA or RC, it was the full release. People will always be able to find bugs and errors when trying to do obscure things that the OS designers never thought of.
They probably don't expect the OS to be used in the manner that people are going to be using it for. Thats why technology has got to constantly upgrade, because users are always making more elaborate programs that rely on API and other OS dependant features. Just because they change some of these around, we shouldn't start panicing that it's going to be riddled with bugs.
At least it can't be as bad as Windows ME
By the way, I have a grudge against MicroSoft anyway, so don't get thinking I'm saying this because im biased 
/ 
