I am happy so far
I've dumped D&D 3.5 for Mongoose's Conan and Green Ronin's True 20 and haven't run it except sporadically for quite a long time. I am thrilled by the coming of 4e:
Likes
OGL
Streamlined Combat
Points of Light Setting (darken the core of D&D up a bit)
Overhaul of the magic system
Wizard Implements (Orb, staff, wand)
NO core setting (no assumed Greyhawk setting)
Fluff can be tossed at will without affecting the game.
Reimagining Devils and Demons
Rethinking the whole Great Wheel cosmology (save it for Planescape)
Having no mechanical impact to alignment (wished they dumped the damn thing)
More emphasis on character less on magical trinkets
Lack of monsters as PC races at the outset.
No unified, thus limiting, ruleset for monsters. (Let them be fantastic)
There will be things that NPCs like monsters can do that PCs can't
Race being a more important and distinguishing part of the character
Weapon choices that actually mean more than just what damage die one uses.
No more PrCs
Elves being more fey and somehow tied to Eladrin (god do I hate the 'S' they add to that word)
No more 'Core Pantheon'
Cautious
Overhauling Fighters and similar (hopefully little or NO wuxia in PHB1)
No gnomes in the PHB1
Tieflings in the PHB1
Rather Unhappy About
Warforged in the PHB1
Asmodeus as a god (meh....pandering to PS fanboys...toss em a bone)
All in all I am happy as a pig in the mud about what I am seeing. I am still hoping that warforged won't be in the PHB1, but we'll see. I know its cool to dislike WoTC, but I think they are on the right track and can hopefully assure D&D's continued survival. I haven't played any edition of D&D that met all of my criteria for perfection thus far...and I never expect to. Each edition has its merits and drawbacks but I think with 4e, at least so far, merits outweigh drawbacks considerably.
I'm looking forward to seeing what 3rd party developers such as Mongoose, Green Ronin, Necromancer and others do with this rule set. Its an exciting time. And its coming out just in time for me to release my own setting...well within 6 monhs to a year of release.
Oh, thank you great gods of OGL gaming.
Sundragon