So so, could have been better. If you're with your kids or are below the age of 14, I think the experience would be amazing. Otherwise, it may be a bit too dull, slow and predictable.
If you have a chance to go to a single show while visiting Vegas, I would choose one of the Cirque du Soleil performances over the Blue Man Group.
I would have preferred if the show was a bit more condensed and had less of the audience work. Involving the audience is nice, but it gets too old.