I would say you didn't miss much after BO II. Although MW was a great game, after this title, not so good.
As you said many people were complaining about crash issues. I did face some lag but the game didn't crash. Everything seems fine from my side and the final release will be great I think.
3rd person mode in cod is like mixing salt in sweets. Didn't even touch that mode.
RE: Call Of Duty: MW2 - Open Beta First Impressions