I think the Wii has a pretty decent amount of interesting stuff on the way before the end of the year (Smash Bros. Brawl, Super Mario Galaxy, Zack and Wiki, Endless Ocean, MySims (maybe), Puzzle Quest, Guitar Hero III, Harvest Moon, Trauma Center 2, Metroid Prime 3). But yeah, it is in a bit of a drought right now. Still, the console itself is deservedly loved, I would say. I was skeptical about the controller, and certainly there are a lot of games that don't use it very effectively, but when it's done right it's really spoiled me for traditional controls. And I'm having fun with the virtual console, the Miis (although at this point the novelty has worn off since I've made pretty much everyone I know (plus I wish they were actually used in games more often)), and even the other channels, which I didn't think I'd have much use for but have ended up spending a surprising amount of time with.
That said, I seem to be the only person in the world who didn't fall in love with Wii Sports. It's okay, but not deep enough to make me want to come back and keep playing it. Zelda was fun, but I wasn't really sold on the controller until I played Trauma Center.
Oh, and talking about underappreciated video games -- if anyone hasn't played Osu! Tatakae! Ouendan (or its American equivalent Elite Beat Agents) for the DS, you really should. I don't know if it's underappreciated since all the critics love it, but I haven't encountered many people who have actually played it.