Over on his blog, Greywulf makes the case for 3rd edition:
He then goes on to list six areas he thinks 3rd edition needs some tightening up. I'd add in the high-level economy issues as well, but honestly, number 4 was a deal-breaker for me, so I'll have to defer to his greater experience with the system.
The thing is, did 3rd Edition need changing that much? Sure there were areas with cracks and problems, but IMHO there weren’t all than many, not compared to the sheer amount of material produced for the game. Most gamer groups I know have put in hundreds (if not thousands) of hours playing it, and the majority of those have perhaps a handful of house rules which “fix” the game in their eyes.
Here’s my list of what needed fixing in 3rd Edition. I’m pretty sure you’ll have a different list, and will disagree with some of my choices; the point is that it’s a very short list, compared to the sheer volume of work for D&D. I’ve bandied about that 2% of 3rd Edition was broken, and 98% of it works just fine - this is the 2%. The other 98% is the rest of the core and all of the supplements. That’s a lot of spells, feats, monsters and classes that didn’t need nerfing at all.
Also be sure to peruse his art while you're there.