I actually rather liked 4th edition. Yes it's simplified, but simplified doesn't mean dumbed-down necessarily. First though, I'm not a very experienced D&D player so you might want to take this review with a grain of salt. I wasn't even alive when AD&D 2nd Edition was having its golden age (i.e. 80s), and have only been playing for about a year, almost always as Dungeon Master (I'd love to be a player but I can't trust my friends to made a good campaign

). Be that as it may, I am a more serious player than your average high-school kiddie, and find the role-playing and plot aspects as rewarding, if not moreso, than the hack-n-slash style of play.
There are some things I really don't like about this new system, first and foremost being the nauseatingly obvious marketing strategies. "Hey guys, how about instead of releasing the rules all at once, let's make three more core rulebooks every year. Think about the sales!" I agree that the concept of the Warlord class is downright stupid. Like a previous poster said, it's like a fighter who can shout. I also, like many of you, think the two most surprising races - the dragonborn and tiefling - are cartoonish, overpowered, and restrictive. I'm banning both from my campaign, and perhaps reintroducing some races and classes from 3.5.
That said, there's a lot I love about the new edition. The rules are intuitive and easy to keep track of: no more heated rule-arguments at the gaming table. This doesn't reduce the complexity of the game, it reduces the complexity of the rules. This produces more time spent actually, y'know, killing orcs and socializing and roleplaying, and less time checking the index of the Player's Handbook. Yes there are some omissions that some of you won't like, but just because there's no blurb on Chaotic Good doesn't mean you can't play a chaotic good character - just no capitalization

I don't know if they streamlined the rules to appeal to a "younger audience", and wouldn't be very surprised if they did, but I like it anyway. Simplification != dumbed-down. It's just a step back towards the openness of OD&D, away from the page-flipping frenzy of AD&D 2E.
While 4E has its flaws, the good changes far outweigh the bad, and the bad ones are mostly of an atmospheric nature, i.e. things that can be easily tweaked by the DM. Not everyone will like it, since a lot has to do with your personally preferred gaming style - hell some of my crazy masochist friends actually *like* thac0, purely for the tediousness of it. I simply profess that simplified rules = enhanced role-playing, and a more open, creative system in general with more room for fun improvisation, not to mention a much fuller DMing experience.
Edit: One more little note, for those of you who want to check out the rules before sinking 60$ into something you might hate, you can find well-seeded high-quality torrents of all three books at isohunt.com