I've seen Blue Man Group twice now, in two separate venues (Monte Carlo Vegas, and San Jose. It's a really great show and keeps you interested with flashy visuals, humor, and creative sets.
There's nothing particularly amazing, especially if you're a fan of Cirque shows. But it's great for families and one of the best shows I've seen all around generally. I will say, there isn't a whole lot of rewatch value. That said, go see it!