I played 4th as soon as it came out, but only the once. My initial reaction was "wow, this is a lot of fun right off the bat! This is great, and I can see why they chose this direction". I found a group of people willing to play, but after some web-research decided pathfinder was a safer bet for my group as they seemed to lean more towards narrative than combat. The only problem I have with pathfinder is it holds true to a lot of aged game mechanics that drive me nuts,
I'm looking forward to that feeling I got with that initial 4th introduction ("wow, all of this makes a lot of sense!"), but as a very basics, polished open-ended framework of rules I can adapt to my own devises.
That's really exciting for someone looking for an elegant, innocuous-as-possible system. It does feel like a bit of a regression, but in the long run, 4th might end up feeling like a smaller blip on the culture than any of the other editions.
Not only that, but the slowing of power-creep of abilities/items, bounded-accuracy, and larger level range for monsters really speaks to the game designer in me.