I've not decided whether I'm switching to 3.5 yet. I have mixed feelings about the entire issue.
The pros: The classes are far more balanced, useful and logical, with a few glaring exceptions (Poke-Mounts for Paladins being the one foremost in my mind).
The cons: At first glance, it seems like a good many of the spells have been nerfed, to use a hackneyed phrase. I know I don't feel comfortable playing a mid to high level caster in 3.5. Some of the changes I agree with (changes to Harm, Heal, Haste and Polymorph) , some I do not (fly being neutered, Overland Fly taking it's place but not until 5th level, and the whole Power Attack fiasco cloaked in illogic*).
I suppose I'm in a position to let the group decide on an individual basis whether they wish to convert to 3.5 or not for their class(es), but I'm going to hold off on spell conversions just yet.
Greg
*2:1 PA conversion for 2H weapons, 1:1 for 1H weapons and nothing for light weapons, except unarmed, which can use Power Attack at 1:1. The whole thing is supposed to address a supposed imbalance wherein a 2W user gets "more benefit" out of PA, except the logic falls apart when the more benefit is expressed as a percentage increase in damage, instead of an actual increase in damage. Monsters and foes don't die because of a percentage increase, they die because of a linear increase in damage, which PA for 2H weapons more than gives out. It's madness, I say.