Just to contrast it with ad blurbs for 3E like this one here...
Why is this new D&D such terrific fun? The new system smooths out all the old rules' quirks and bumps, creating gameplay that is easy to understand and quick moving, yet with more depth than ever. Combat is much easier to conduct, but it's more exact, always making it clear exactly what's happening. The full-fledged skill system allows characters to do many tasks that fall outside their stereotypical roles. This means that characters in the same class aren't all clones. A fighter can be a slow brute with an axe or a lithe, rapier-wielding acrobat. All this customizability leads to more engaging characters and more opportunities for roleplaying.
....which for some reason sounds, in a lot of things, like the stuff being touted for 4E now. Faster, smoother gameplay, quick but exact combat (heh), characters in one class that are very different from each other, fighters for whom weapon choices can make a difference (sound familiar, anyone?), more engaging characters and more opportunities for roleplaying.