Actually, there's very little about 4e that I've heard so far that I don't think sounds at least marginally better than 3.5. Oddly enough, the attributes of 4e itself will probably have very little impact on whether or not I buy it. Rather, the factors that will make my decision include:
1) I'd rather be playing something other than D&D anyway. I'm not interested in a major investment of yet another D&D system when D&D is my "compromise solution" rather than my actual preference.
2) My huge investment in d20 and D&D products. With what I currently own, I can run any game in any genre and any style to my satisfaction. Because there's a high degree of cross-compatability between all my 3e, 3.5, d20 Modern, d20 Star Wars, d20 Call of Cthulhu, Arcana Unearthed, Midnight, Iron Kingdoms, OGL Conan, etc. products any switch to 4e even if the system is tons better means an immediate drop in the quality of my game due to lack of resources relative to using a pre-4e system.
3) Group inertia. At the moment, my rather indifferent attitude towards 4e is the best of anyone in my group. Everybody else has made a firm statement that they have no interest in updating.
4) Budget. I've got other things to spend my money on. During the heady days of the early 2000s, and even fairly recently I had plenty of available cash for picking up D&D books, but now my wife and I have reallocated some of that "petty cash" to other interests.
5) Interest. Honestly speaking, I'm just not that excited in general about the hobby these days. I still enjoy both playing and running, but the fires of excitement have burned down to some nice solid coals. They'll be warm for a good while yet, but I certainly don't feel that excitement to be up to date with all the latest and greatest material anymore.
All of that adds up to a 4e that I think will be markedly better than 3.5, but which I probably won't buy anyway. In any case, I won't be an early adopter, and I won't buy it until I've had a chance to read through the SRD or the books themselves in some detail. And I certainly don't see my adopting 4e "whole hog" even then. I'm simply not going to get into the supplement "arms race" all over again.