Just downloaded it and played it. And...wow. The new interface is much better than the old game, the new weapons are cool (I LOVE the mine layer!), and the vehicles rock! Graphics are about the same as some of the better player-made levels for UT2K3 - which is to say pretty good. Much better than the "stock" levels from UT2K3 (at least a couple of the levels look better). But, the engine is still basically the same as UT2K3, so no major improvements.
Can't wait to nab this one (along with Doom 3!). And one I sell this POS on Friday, I can order my Athlon 64 with a new video card to help play those two games!
A bonus: it looks like the map format is the same as UT2K3's (should be, anyway...basically UT2K4 is just a tweaked UT2K3). This is good, since I have about 400+ UT2K3 levels.
I WANT THIS GAME!! And Doom 3. HL2? I could care less about. Gimmie gimmie gimmie!!