I've looked over much of the previews, and there is much of the concept and setting that I have liked. But when it gets to the mechanics,...I'm reminded of the direction R. Talsorian's Cyberpunk game took; I'm left with the impression that it caters to a videogame and MMO demographic and player choices are 'dumbed down' to match a belief that the consumer has to be spoon-fed concepts.
I've seen much of the concepts I find exciting, with a reimagining of the of game with intriguing new cosmologies, races, character concepts,...but the execution I find lacking. Certainly 3.5 is not perfect and I freely admit I tweak it to suit my needs. But I think that's what has made 3.5 (and variations) so good is that they can be tweaked. I can see the core concepts and mechanics and can tweak them to meet my needs in most any setting. 4th Edition, while having a very bright and appealing look to it, just seems very restrictive in the end.
While I plan to eventually pick up the material as it comes out, right now it seems more likely I'll look it over to draw ideas and concepts from and then convert over to 3.5 mechanics.