I run a game, which had pretty much been running to an end regardless. So when that game ended I started a new one using 3.5 and it's been fine. I believe 3.5 is totally superiour to 3.0
However, I"m in three other games.
One is run by a person that hates 3.5 because they "nerfed" everything. She picks and chooses from 3.5 as well as various other things (such as AU). So in that game I'm a 3.5 bard/ 3.0 paladin/ 3.5 Dragon disciple.
ANother DM has the 3.5 books, and wants to change, but the above mentioned player is very much against it, so he keeps putting it off. She does the same picking and choosing to make her characters stronger, but she's addicted to 3.0 haste.
Last DM doesn't have the 3.5 cores, though he mentioned that buying new books that reference 3.5 is a bit odd. Same player opposes 3.5 while abusing her Haste boots.

She did get him to allow some of the armor 3.5 enhancements that benefitted her character.
My main problem with teh games that dip into 3.5 is that the dips are unclear until they come up. I've tried convincing the Second DM above to adopt the combat chapter at a minimum, so it's clear exactly what rules we're using. (especially since i think 3.5's combat chapter is much better written.) He still "thinking about it" and will probably never act on anything.
So, my experiences with 3.5 are more based on individual bias rather than any effect they're having on the games. DR is a perfect example though of something that bugs me, since I like the new DR much better.
Oh well.