It is. Really.
But it's so fun. And given how infrequently I see them in stores, Nintendo is having a hard time meeting demand for the Wii. Even at a million-plus units a month. But it is fun.
In some ways, it's a return to the days where games weren't dependent upon high-end graphics processors, and 'realism' meant that everything was made out of blocky pixels. The Wii has better graphics than that, sure, but the lack of concern for uber-realistic rendering is still there. Characters with bodies, and hands, but no arms. Or disembodied hands wielding fishing rods and ping-pong paddles.