A ground-up mending of 3e's problems, basically.
The rituals were a wonderful solution to a "wizard can do anything" problem.
Adding variety and power to fighters and the like (e.g.: a sort of martial powers system) solved their vanilla problem.
Evening out The Maths and introducing a new save system (and getting rid of most save-or-die effects) solved the swingy combat problem at high and low levels.
The skill system needed consolidation.
The monster-building system needed streamlining.
The "conditions" are great and consolidated (especially simplifying grappling). Ability damage needed to stop the massive cascading effects that it triggered.
I would have also liked to see more work done on the DM support side, a step-by-step analysis of building an adventure into a campaign, and, perhaps, advice that concentrated on being simple, straightforward, and elegant, introducing people to D&D one small step at a time.
The "20 minutes of fun crammed into 4 hours" was (and STILL IS) a legitimate problem.
What I didn't really want, or need, was a re-examination of what D&D was. I knew what D&D was, for me and my players. I had been playing for years with the style I wanted. I had brought on many, many newbies. I didn't need to be told that the simulationist and narrativist elements I loved were getting in the way of ALL FIGHTING ALL THE TIME, which I didn't even like that much in 3e because of the grid-based nature of it. I didn't need to have this tremendous wall of accessories, time, and space between me and my D&D game. I didn't need the Vancian system to take possession of my game like some Cthuloid horror of universal class symmetry (I didn't LIKE wizards in previous editions, dudes!).
What I needed was a way to play my game better, not a way to play WotC's minis combat game.
