I can sum up why this is the best in fast playing super hero table-top gaming.
Any Hero, Any Power, Any Scenario.
Structured enough to provide excellent relative differences in powers, enough depth to include a full campaign system (with RPG elements and character progression if you wish to use them) and flexible enough to emulate virtually anything you've seen in a comic book.
I have been a fan of Four Color's Super's games for some time. This 2nd edition of Super Mission Force is the latest version of an already excellent game. The goal-system method of game play is perfect for fast-paced, super powered, skirmishes. You can easily fit two full games in an afternoon. If you haven't tried this game before, don't wait. It's a bargain at $10 bucks.