DerNater and other people who claim that 4e has just as many builds as 3e -- dudes, irregardless of which game is better, you are just totally wrong.
It's arguable that non-spellcasting classes have more builds, I'd have to really count it out. They DO have a lot more interesting powers. But clerics and wizards have about 1/10th of the builds they used to have. (And yes, I know that the typical 4e-fan response to this is "They had it coming." Sigh... ~_~ But it's not just the wizards who lose, it's the whole game world because the spell list is gone and now even bad guys don't have interesting spells to choose from unless you make 'em up from scratch! It would have been interesting if the 4e DMG had an expanded power list to fill these gaps, but I guess we're forced to wait for splatbooks.)
However, the other classes have also been "narrowed" in significant ways. As a general design principle, I far prefer 3e's basic idea that "your class is something that gives you a bunch of stuff, and you can mix and match classes to get different combinations of stuff" rather than 4e's basic, simpler idea that "your class is Your Class, and these core abilities will always be your Core Abilities." 3e is vastly more flexible. You could start out as a 1st level fighter, change your mind, take the next 6 levels in rogue, and presto -- you're more rogue than fighter. In 4e, if you start out as a fighter, you are pretty much gonna be a fighter for the whole game, doing your duty in the Defender role, whether you get tired of it or not.
I'm also not interested in hearing people complain about how animal companions and familiars and henchmen and animated undead and summoned monsters slowed down the game, and so forth. Sorry guys. I've heard this about a zillion times on forums. Yeah, they kinda did slow things down, to be honest. But, they were still FUN. Just like disarming, sundering, tripping and all the other stuff that you COULD do in 3e (of course, 4e has the hand-waving rule, I acknowledge, and yes, grapple in 3e was confusing). The potential imbalances of these rules are all the kinds of things that an experienced DM can work around. That's what gaming is about: the DM knows in advance what the party's abilities are (unless you're playing a tournament game or something), so if they're a good DM, they *don't* force your 3e rogue to encounter tons and tons of Plants and Undead and Constructs. ~_~ It works both ways, though; the DM also tries to challenge the characters knowing just what will challenge them the most; she sets up a scenario, an adventure; the players try to compete in it and/or break it.
(Yes, breaking it should always be an option. If the players find some hole in your adventure, if they kill the big bad guy with a Finger of Death, or use Discern Lies and discover some clue they weren't supposed to discover, or whatever.... then the DM's gotta roll with the punches and make the next challenge more challenging. No campaign is, or should be, airtight... that is called railroading.)
Does 3e have a lot of BAD potential builds? Well, yeah, of course, this is part of the fun of tinkering with the system (more for non-newbie players, admittedly). I've played several optimized characters, but also several non-optimized characters -- hell, I created all my 3e characters with die-rolling in the oldschool 3e fashion, so of course I was *forced* to play non-optimal characters when my stats were bad. And That Was Just Fine. D&D isn't really a game about winning combats, after all. It's a game about wasting time with your friends and making believe you're in some fantasy world. (AND winning combats.) If I want to spend 8 skill points on "Profession (Cook)" instead of "Concentration" then why the heck not? ~_~
And if one of the other players later says "What the hell, Jason! Why didn't you maximize your Concentration, now our whole party is going to die because you got hit while combat-casting!" then... THAT'S NONE OF HIS BUSINESS. ~_~ The individual player's desire for their individual character trumps concerns of team unity and character roles, IMHO. Like I said, D&D is not all about winning combats. If this makes you think "Wow, you must be a bad player to play with," then think what you want. (Let's see, what's the most un-team-oriented thing I ever did... I once attacked another PC in mid-combat because I was Neutral Good and he, a Neutral barbarian, was going to spend his action to coup-de-grace a person who'd surrendered. Hey, I warned him first.)
Likewise, I think the de-emphasis on alignment is something which is aimed at making the game simpler for newbies. Now the default assumption is "The game is heroic, so you'd better be Good, Lawful Good or Unaligned. Otherwise, you will make the other players angry with you." This is very sensible advice for a bunch of newbie players in elementary school or junior high, in which there's always one guy who plays Chaotic Evil so he can derail the plot and screw with the other characters. It's NOT necessary advice for more experienced role-players who can actually roleplay these alignment differences in the spirit of fun, without getting mad at one another. (And yes, of course, in the grand scheme of things there's no need for an alignment system at all... but hey, this is D&D we're talking about! So I'm talking about the things that, to me, make D&D D&D.)
Okay, now I've really been rambling. So what do I like about 4e?
* Well, it's a good-looking set of books. The art is good.
* On a "personal bias" level, I like dragonborn (sort of) and tieflings.
* It's a good intro RPG for newbies because, frankly, it's a lot simpler and easier to start playing than 3e. Also, the fact that 1st-level characters are stronger is a boon for appealing to newbies.
* The new miniatures-oriented rules frankly look AWESOME. If you're going to play with a miniatures mat, then it makes the game a lot more fun to move the miniatures around more liberally and push people into walls and pits whenever possible.

* They wisely made the math a lot simpler. It seems a lot easier to figure out, on the fly, effects of range and movement and what-effect-does-what. (Because there's no Ability Score damage or buffs, because movement penalties and bonuses are in the form of flat positives and negatives rather than "half" or "quarter"... etc.)
* After some consideration, it was a good idea to remove Skill Points and just go with straight trained/untrained. Much simpler. Skills always took a lot of time in chargen for relatively little result, I have to admit.
And here's what I don't like, not counting the wizard-and-cleric-nerfing, which obviously is just me being a whiner about my favorite classes: ~_~
* Significantly less variety in character builds. Class is much more of a straightjacket to characters, lacking the mix-and-matchability of 3e's multiclassing and prestige classes. (Admittedly, of course, this was just something in 3e, not in any previous editions. I guess I was spoiled by it.) Emphasis on character roles is a tradeoff, making it easier for new players to understand what D&D is all about, but reducing the core charm of the classes in some ways.
* Characters' abilities, and monsters' abilities, are significantly more combat-oriented and lack flavor as a result. Extreme, extreme emphasis on ritualized encounters and combat.
* While the increased simplicity of the basic rules (simpler math, etc.) is a good thing, I am disappointed that the 4e DMG is missing a lot of the "simulationist" (there, I said it) world info such as the climate-based encounter tables, hardness for dungeon walls & formations, wind speed, this, that and the other thing.
On the whole, I'm forced to concede that (unless you're one of the people who likes roleplaying but doesn't like miniatures) 4e is a more appealing game for newbies. As for myself, though? 3e, definitely 3e.