I went to see it last night. It features Will Smith playing a disguntled superhero. He isn't thought well of, but he saves a PR guy who hatches a plan to solve his reputation problems.
Without giving much more of the plot away, I enjoyed the movie. Not a great story, but it was fun, especially I thought at the beginning during his misadventures, many of which were in the trailers prior to the release. My favorite being the one where he saves the whale by throwing it back into the ocean, but takes out a sailboat in the process.
In many ways, his misadventures reminded me of Bruce Almighty. The ending is cute enough. I wouldn't recommend a sequel, but it is definitely worth a rental if you skip it in the theater.