I ran this as a conversion to Mutants and Masterminds with 5 players over the course of 3, 4 hour sessions. We really got a good amount of time in this one.
The basic plot worked really well though perhaps an introductory mook battle with someone other than the 4 villains featured throughout might have added greater diversity to the encounters. This is what I did and it seemed to help. The villians are interesting and quite thematic which worked very well and had interesting powers that could challenge the players on several levels.
I also enjoyed the investigation aspect of the module. Its clear and well laid out. Has a couple of good RP scenes which give the PCs a chance to establish their personalities outside of combat.
The finale plays out interestingly enough though requires some work by the GM. We are told that the BBEG can be tricked up yet offers little examples on how. Not too terribly difficult to work out on your own but some good examples would have been nice.
Overall a great product and clear plot if your looking for a simple superhero RPG story to utilize in your game.