Same problem with my mid 2012 MBP 15 non retina.
Mainly having the freeze when starting WOW - I did not have issues with the previous OS on my MBP.
Update: whenever the graphic card changes from internal to discrete the crash happens, either starting a video, a game, just open a website which needs more graphic power => freeze
I like my MBP but seeing that such a software issue is not fixed and mainly ignored by Apple makes me wonder if I should buy a MBP again when my one dies - seems no support at all.
Still frustrated about this issue (as the MBP works fine otherwise)