I have been DMing the playtest packets since the first release, and my group and I are having a blast. I have no real complaints. I find the rules very freeing and fun. Over all I think this is going to be a good edition.
The one thing I am disappointed with is that there seems to be no mechanism or design for the system to become modular.
Instead they seem to just be making a very vanilla and loose D&D system reminiscent of first edition without the murkiness. I am find with that. I think that is great, but I was very excited by the idea of there being a modular aspect.
I think being able to swap in different sub-sets of rules (maybe even from game to game or from encounter to encounter) would be great.
It seems like this is being ignored. Perhaps I have missed some announcements or other discussions?