APEX is the latest in a great line of supplements for 4th edition D&D. I use the term supplement in it's truest sense, all of the DEM products bring completeness to the 4e library of games.
APEX is no different, it brings to the table a great set of rules to use with almost any kind of super hero genera. From X-men to jumper, its a good tool kit for an supers game.
Though there is a bit of a balance issue, namely there isn't much. But it is part of the whole super experience. But once you can get past that the game looks great!