DC Adventures Hero's Handbook is a fun game.
I should probably preface this by saying that I'm not a M&M guy. I can't tell you what's new in this and what's old.
However, I can speak for this: It's a full game set in the DC Comics universe. There are various blurbs on setting and characters, though you'll probably already know this as a general rule (since most of the target audience consists of people who have at least been exposed to the likes of Superman, Batman, and Wonder Woman).
More impressive is the sheer volume of the game. It's huge. 281 pages, lots and lots of pictures, and giant walls of text (which are admittedly broken up a fair deal).
While it's a lot to read in even 5 sittings (it took me 7, and generally I get in 100-150 pages a sitting), it's got nice solid rules, though it feels very different for a veteran D&D or Shadowrun player expecting walls of rules for things. Pretty much everything is handled by a single d20 check. Look through the giant text, and you'll find that maybe 50 pages max are devoted to plain rules, and the rest focus on content.
The downside to all this content is that it's massive and takes a lot of comprehension. Quick reference? I'll believe it when I see it.
All in all, my only real gripe with it would be the incredibly massive modifiers on a d20, but I state that gripe for almost every game that uses 'em, and in a superhero setting, this is more forgivable (after all, why shouldn't Super-Tough-Character be able to shrug off a paltry bullet 24/7?).
For $20, this is a lot of bang for its buck, and the plentiful art and well-designed game work well together. A must for any comic book aficionado or a GM/player in need of a superhero game.
And, despite the name which might hint towards the book being oriented for a player rather than a GM, the book does do both, it actually has quite a few pages devoted to the GM.
5/5 in my book, because its quality and setting are top notch, and the art is premium.
[5 of 5 Stars!]