Fitness and Kinect

Has anyone actually used the Kinect for fitness purposes?

If so, which games are the best?

There are already a slew of fitness games (and reviews for them) available.  But I have better things to do than slog through a ton of maybe-helpful reviews.  So I thought I'd see if I could get the scoop from people who've actually played the games.  I trust actual users more than some overweight pundit reviewing fitness games!  (See following video.)

I'm particularly interested in Your Shape: Fitness Evolved, since it was created by the publisher behind Men's Health and Women's Health magazines.  Men's Health has pretty good fitness tips, so I'm wondering if that expertise translates to the game.

Has anyone played Your Shape: Fitness Evolved, or any of its competitors?

You can see a list and details of the fitness games available for the Kinect here.  (Currently those games include The Biggest Loser: The Ultimate Workout; Your Shape: Fitness Evolved; Get Fit with Mel B; Zumba Fitness; and EA Sports Active 2 for Kinect.)