I have to admit that Mario Kart Wii's online was better than I expected, it's not hard to just hop in and find games. Although half the people I know who own the game are those filthy females who decided to have like kids and families and crap instead of playing moar games, the rest being those OMG SO MUCH DUST BUT ZELDA EVENTUALLY types so I don't really know how it functions trying to play with friends (I think the one attempt failed, I assume it did anyway), but playing with randoms works pretty well, very little lag too. And people playing it online at my place have seemed to enjoy it.
And the few posts I read about the community thing seems pretty neat and a way around Nintendo's whole desire to control everything.
Nintendo fans are basically experiencing how PS2 online was for a long time. I could be biased though, I expect to be on the PC for online gaming so I get strange amusement out of the Wii online working as well as it does in certain games. So I try something and then get compelled to go "this is really working? wait..." and play it more than I should.
You take something like BLOPS or GoldenEye and they work on their own system and seem to run pretty well. Other games...I tried the Conduit 2 and it was pretty shoddy. BLOPS seemed to work better overall than during the Steam Free Weekend for it or MW2 in terms of actually matching ping. I guess Treyarch worked in a way to patch the game on their end so both it and MW3 get patches without having to deal with Nintendo.
Not saying it's great, it's not, but I can see where examples of an actual functioning online can make you excited about the future of multiplayer gaming!