After DMing 3.5 consistently for about two years, yes, I am very much looking forward to 4th Ed, especially from the DM angle.
3.5 is one of those systems that looks great on paper/in theory (internal consistency – monster follow the PC rules etc), but breaks apart in practice in my experience, especially at the higher levels.
I'm still having a blast running my current 3.5 (well, 3.75) Planescape campaign, but like most things I see need for improvement.
I'm very excited about the removal of the full attack action and more movement in combat etc. That is one thing that often bothers me about the current system for melee types, is that they often get into a position to full attack and then stand there monotonously hacking away until either they or the enemy drops – boring.