SMG2 is as clever and fun as the first one. The primary tangible change is to the 2-player mode, as the second person can now have a real affect on the game beyond collecting starbits. They can now spin attack (and often kill) enemies, and can grab coins, 1-ups, and red mushrooms (which makes some of the level design redundant, as there is no longer any risking in grabbing said items). I'm of mixed minds; it means that it's more fun for my fiancee, but it really does take the difficulty down a few noticeable degrees. But if you loved SMG1 (and why wouldn't you), this is an easy recommendation.
I've also recently gotten Monster Hunter Tri, and I'm still uncertain if I can recommend it yet. I'm having a surprising high amount of fun playing it, but I've got a nagging feeling that the 1 player mode is going to wind up being an extended tutorial for the online mode, and I don't see myself wanting to wander around the City looking for group, or investing in a Wii-speak.
It is the policy of the documentary crew to remain true observers and not interfere with its subjects. "Well. Shit." -hansen9j
Bought SMG2 on release day, and now I'm 42 stars in. Love it, even more than the first. I kinda like the co-op mode, as my girlfriend liked collecting star bits as I played in the first game and now she feels more involved and hey, it helps me out. The music is fantastic, the levels are creative and fun. My only two complaints: the galaxy where you're flying with the bird and Grimace, or whatever the chubby purple luma is named. He jabbers on way too much and keeps telling me to take a break.
I LOVE that the rosters are now 70 per team, so that you are less likely to have to start a true freshman CB because five graduated or left early. (I hate that it's going to take me that much longer to input my rosters, however.) I love transfers.