As I hinted at the end of yesterday's discussion of some of 4E's limitations, there's another more important distinction between 4E and 3e. In the new edition, each character has roughly similar capabilities. Sure, there's the striker/defender/leader/controller thing, and the variations on each of those themes, but it's all pretty much doing damage and deciding when to use your encounter powers and whether to burn your dailies. Occasionally you stick some interesting effects on the monsters, and there's a fair bit of moving around, but it's all just variations on a theme. It's a fun theme, and if the DM is on the ball you can get a lot of mileage out of it by changing the environment and monster behavior, and even more by building different characters in different ways.
But it's all one kind of fun.
There are a lot of different ways to generate varieties of fun -- call those ways the dimensions of fun, if you like fancy phrases -- and 4E drops a lot that 3.x had. One of the big ones, the one it had to give up to get the tactical complexity it's designed around, is variation on the mechanics behind character powers. 3.x has feats, skills, Vancian magic (of divine and arcane quality), psionics, incarnum, shadow magic, truename magic, binding, whatever that dang Tome of Battle stuff is, plus a bunch of class specific doo-dads like bardic music, rage, and dragon shaman auras all stuffed under "special abilities." All of which makes characters a lot harder to build, and a lot harder to predict how everything in the greater system will interact, but it allows for tremendous variety in the way the game plays. It also opens up a lot of headspace, creating a convenient source of ideas on how societies and environments might interact with the powers that drive them.
4E has one way. It's a good way, but it's not the only way.