I posted most of this in the 4th ed. GURPS thread, but I think it's applicable here.
Have a fair # of 3rd ed. sourcebooks, as well as the core books, just sitting around on a shelf. My g/f likes the basic info contained in the sourcebooks (she's a history buff).
But, as nice & generic as it is, it really feels uber-detailed to me--a lot of detail that needs to be kept track of.
I'm not sure if there'll be as significant of a shift from 3rd to 4th (vs. D&D's shift from 2nd to 3rd)--rather, it may more or less be more comparable to D&D's shift from 3.0 to 3.5--esp. with issue regarding 3rd ed. sourcebook capatability with the core 4th ed. stuff. Honestly, if that's the case, I'm not too sure I'm give this newer version a try at all.
Then again, I do feel that "less = more," and don't care for a strong push toward capturing reality in games, since there's often a strong urge by some players to use that reality in order to help them break it (if you catch my drift).
Though I do love the polyhedral dice, just using d6's makes it a bit more accessible (to a degree)--heck, you'd just need to buy a brick of d6's, or at least raid a bunch of boardgame boxes &/or buy some pairs of dice in order to be equipped for the game. Keeps things somewhat simple, in that regard.
I also like the idea of point-buy for PCs, since it (generally) allows each character to start on even footing. However, as mentioned before, w/ GURPS characters w/ the same # of starting points not not necessarily mean or = evenly-balanced characters.
But, I think 1 of the big things about GURPS that gets to me is, from my experience, there seems to be a lot of hard-wired mechanical aspects/bonuses tied to things that could merely be covered via roleplaying, such as personality quirks & the like. Also it seems that some very liquid elements about characters--things like wealth, contacts, possessions, reputation, etc.--seem a bit more hard-wired into character creation as well. These things seem too easy to lose & gain for a PC, esp. through roleplay (if not, then things seem a bit too static for a PC, IMHO).
Also, I'm not a fan of uber-detailed combats. The more a combat is stretched out by additional levels/processes/details, the slower combat feels (& doesn't help to add to the feeling of a fast-based, urgent situation at all).
I understand that some may like to include things like this, &, of course, it's up to the GM to include/exclude things as he/she wishes. However, IMHO, I prefer that things merely be added into a game to include them for those who want them, rather than having to take things out to achieve the same thing.
Of course, that's just MHO on the matter. I think that, despite the revisions, GURPS (like D&D, WW WoD, and many other RPGs) will fit into a particular niche, and maybe expand a little, but I doubt that it'll bust out and take over other niches held by other games.
With many of the things mentioned in this thread, there seems to be some decent ideas/concepts in the newer version, as well as some redeeming decisions (like the uber-stats being more expensive to develop). However, there are some things that I'm still not to crazy about w/ GURPS, & will ultimately prefer using other RPGs for. Ironically enough, GURPS may be generic enough to use for various genres, but for me, it'll be used only for certain kinds of games/types of campaigns, & not as a truly universal, generic system (basically for me, it winds up being a niche-oriented game as much as D&D and Marvel Super Heroes are).
However, I am a big fan of Denis Loubet's artwork. That's always a + for me.