Ok, so I just played the demo, and oh my word, this game is already better than LoS. Obviously its the E3 demo, so some of this may be old news, but here are my thoughts:
-The combat is faster and more responsive. Playing as Dracula feels like playing as Dracula. Your dodges are smooth, and the transition between different weapons is seamless. The only thing I missed in the demo was a move list, because I was ready to experiment with the combos. And if anyone felt like LoS boiled down to mashing the X/[] combo over and over again, LoS2 makes you want to mix it up, particularly because I felt the enemies put enough pressure on me that mixing in AoE attacks was important, rather than just an option.
-Enemies are more varied and have way better AI. Just tossing in shields that you have to break with the Chaos Fists before doing anything else was good for me, but then you have the fact that enemies capitalize on you being knocked to the ground, and even just move a bit quicker, and it's way more fun to interact in combat.
-The music is better. I loved the LoS soundtrack, and thought it was very atmospheric and well composed, but sometimes it was lacking a little something-something, going more for grandiose-ness than energy. IMO, the new soundtrack has energy.
-Platforming is completely better. It's still shimmying-style, so that hasn't changed, but it's quick, quick enough that you still feel entirely in control even when you have to jump through moving cogs while the gold paladin dude is shooting fire arrows at you, something that would have been a clusterfuck nightmare in LoS due to the clunky wall-shimmying.
-Titan was more fun. It was a set-piece and an event, rather than some big stone...thing in a flat room that you just had to fight by crawling all over it like an annoying tick. You fight soldiers on it while its slamming its fist into the castle, jump through cogs ala Clock Tower (LoS) while the Paladin is raining fire arrows down on you, then you have to jump around it while using the paladin to destroy the bolts nailing the titan together. I mean, if you HATED the Titan fights in LoS, I can't guarantee you'll like this one, but there's definitely more to it.
-The atmosphere is more "Castlevania". I'm probably one of the first people on this board who will defend LoS's right to call itself a Castlevania, but the demo of LoS2 just had more of that essence of "Castlevania" that started showing up more in MoF. Can't explain this one much more than that.