IMHO
3.5 was little more than a random collection of poorly written, edited and play-tested house rules. The new edition solved a few problems, created a bunch more, and at the end of the day did very little to actually improve the over-all game.
To this day, of the 30+ players and GM's that I am in contact with on a regular basis, not a single one uses 3.5 fully. Most of them integrate a couple of odd rules into their 3E games, but nothing more than that. The most common rule changes involve character classes (bard & ranger) and a couple of spells (Heal & Harm).
3.5 was one of the main reasons why my primary gaming group switched over to AU.