I don't much care for pathfinder. I looked it over. Some things are "improved." Others aren't. Overall, it simply isn't worth learning the new system for some questionable improvements over 3.5, not when I already know 3.5 and enjoy it just fine as it is.

If you have some sort of problem with 3.5, maybe pathfinder changes that particular thing, but maybe it doesn't. Look it over and see if it does. But overall, unless you're dissatisfied with 3.5 for whatever reason, I'd just stick with it as is. Well, not only would I, that's what I am doing.

P.S: 3.5 fixed Fighters. They just misspelled the name of the class when they released the update - it's spelled "Warblade" now.