Well, I have not really played online multiplayer much with Uncharted 2. With the release of the new DLC and Double Money weekend, I thought why not. 
 Well I played several hours of the weekend, and I really enjoyed it. The game is quite balanced for me, and I do like the progression of the unlocks and gaining money to purchase the upgrades. 
 
I got a few games of the co-op modes also, really enjoyed those also. Working as a team to defeat waves of enemies is great, but now with the Siege mode, thats also cool, and enjoyed the rounds I played of that. 
 
all in all, Uncharted 2 did a great Mutliplayer component for their first in the series. 

I played a very limited amount shortly after release and very much enjoyed what I played.
 
(...I woulda played more but you know, so much to do, so little time)