They've ONLY to:
-Fix the overlapping/extreme music volume in the MP Menu
-Fix the LAG and the Netcode (better Host Selection by region and Lowest-Ping at least, and fix Host Migrations. Or even better: DEDICATED SERVERS)
-Put a really simple RANDOM filter in Maps Rotations in every Playlist instead of the same map rotation everytime
This is it for me with stress on:
-Make Host Migration WORK!
If it was successful at least half of the time then that would be an improvement. I would love to see Crytek's internal stats showing the global percentage of successful host migrations in this game. If it is over 20% I will be amazed.
Compare this to my experiences with host migrations in Reach (~90% success) and Black Ops (~80% success) and you can understand the frustration with the online play....
On topic - I will definitely be getting Brink in a couple of weeks, and depending on how good Brink is then that will mainly decide on my C2 disc's fate. The only way I can see myself sticking with Crysis 2 is if the issues above are addressed and there is an announcement of a kick-ass DLC!