Currently I'm 6 1/2 hours into the game at 56% (got my copy early from AMC event). So far I feel (this is coming from a massive U1 and U2 fan).
+Platforming couldn't be better....been really precise.
+Combat is greatly improved where you get to do more.
+Locations have looked great too.
+I feel multi-player was better, but that's only based on Subway (not full game)
-Pacing just isn't as good as U1/U2. U1/U2, I didn't want to stop playing, where U3 I sort of want to break after a period of time a bit too much. Maybe R3 just did a better job hooking me in.
-I haven't experienced much cool variety in the gameplay yet, but might come later.
-While some may prefer the harder puzzles, I definitely don't because the journal can be pretty worthless on helping you out on some (especially a certain one in Chapter 11).
-Game definitely has some hiccups, such as glitches, wonky camera in some tight situations, and some areas seem to not have that great of graphics.
I'm pretty neutral on the story and soundtrack. The story seems good so far, but not extremely strong. Soundtrack mostly seems what I heard before TBH.
I expect the game to get even better, but right now I find the game great, but definitely not one of the top 5 games I played all generation currently (I rank U2 and possibly U1 that high).
And please, definitely buy the game on release if you want it. Definitely worth it to me.