Oh god... I hate this thread. I didn't read everything, but it's basically another thread where people can't accept that others have different opinions. And not only that, people judge again games (or in this case betas) they haven't even played...
I have a few things to say (especially about graphics). First of all, I haven't played the Gears 3 beta, so I will NOT comment on that. Now about Uncharted 3: it's a BETA, so I can't really understand why some people expected it to look way better than Uncharted 2's multiplayer. We also don't know how old the build is, at least I haven't seen a confirmation if it is the latest one (not sure about that one, but show me a link if I'm wrong) and even if it is, it doesn't mean much. I remember UC2's mp beta which looked significantly worse than the final product, I also remember Crysis 2's mp beta just a few weeks before its' release which also looked significantly worse than the full game in the end IMO. The beta has problems, but hell.... it's a goddamn beta! A beta is for finding bugs, etc. and not (only) for people to try the mp.
Well, I wasn't really a fan of Uncharted 2's mp, but so far I liked UC3's beta a bit more than the beta of the second one. In the end I will probably just play the co-op modes for a longer time.
So finally... just buy the game(s) you want. I will buy both, but mainly for the sp and not for the mp.