for what its worth
i was one of the people who was initially hesitant about 4E because i was quite enjoying both DM'ing and playing 3,5E
4e now its released is very obviously a different game from 3,5e with a different approach required (not saying good / bad, just saying different)
pathfinder (and i've playtested alpha 2 & 3 with my regular group) seems to fall into that middle ground of being recognisable, interchangeable with my books, but have some new ideas that seem to fall into the category of 'very common house rules' with the added benefit of being thoroughly playtested and pulled together as a consistent system.
like most changes, it will fail to please all of the people all of the time - (just look at 4e's reception...) but it offers an alternative approach that is worth applauding, regardless of wether its an approach that you will adopt whole heartedly, mine for ideas, or sidestep completely
If you love 3,5e - stay with it!
If your moving to 4e - enjoy!
if you want to tweak 3,5e without going to 4e, you could do a lot worse than pathfinder