Guess I'll start us off!
Crysis 2 MP Beta was fun, then the full version came out and the shite hit the fan at first with Activation keys not working and stats not being saved etc. Then those got ironed out and it was fun again, then the hackers found their way to the servers and that was gg for me.
So I'm really hoping they've found a better system to keep this crap out the servers and that they learnt from all those previous mistakes. Honestly I'd rather wait and have them properly test and fix those types of issues than have them rush through it to meet the deadline...