The Island is a big, noisy, empty movie. It perfectly fits the bill of the summer popcorn flick. You won't learn anything, you won't leave with any lasting impressions, and if you don't see it on the big-screen, then you're missing half the point.
This movie never tries to be anything more than it is, and I can appreciate that. After the relatively quiet beginning, the viewer is never forced to go very long without gunshots, explosion, or car chases. Some of the action scenes are actually pretty epic, and if you end up remembering anything about the movie after, I'm willing to bet that it will be a few of those.
So as an average, disposable summer movie, The Island is a success. There's little reason to see it again after the first time, though. That's like watching the same exact kind of fireworks twice in a row. Sure, they're still pretty, but the novelty has worn off, and you're ready to see one of the other countless kinds of pretty explosives.