Commonly only the ones having problems leave a (unfriendly) comment. Wouldn't it be nice to have another indicator than "3 ranting users" on how safe it is to install the update?
In fact, those who successfully update rarely register on the forum just to say that everything is OK, also because can you imagine the lot of useless users?
Don't know. In 7.20 it currently looks like 10 of total 10 votes for "there was an issue not able to resolve" and no others. That would significantly warn other users.
I had the feel that 7.20 beta and rc phase was very long and not rushed (like 7.18 that was pushed for RDS). And many issues have been discussed and fixed in the testing phase. And now people crawl out of their holes on day one of stable release yelling: Stable my a**!
C'mon, it is always the same in ever 7.x major release.