Honestly, I may sound nit picky here, but it only takes a few minutes of unimpressive footage to keep me from buying a game.
Vanquish Demo -- "Nice Nice, looks sweet. Ok the slide animation is a bit wonky but whatever. Good lord these cutscenes are awful. Sweet melee. Eh..cover shooter....cover shooter....boss with big red weak spot.... I think I'll save my $60"
As for Castlevania, that was something I've been hyped for since the first trailer. I was always skeptical of the combat footage, however. And I very well should of been, because this new footage basically displays a horribly run-of-the-mill action game that I've been playing for the past 5-6 years.
Hack-Hack-Hack-dodge roll-Grab-Hack-Hack-Quick Time Event. It's flat out unimpressive. Even though GoW III is esentially the same thing, at least they squeezed every last bit of potential out of that formula.
cLoS basically looks like a Dante's Inferno, except it will probably have a pretty cool narrative. In the latest developer walkthrough where he plays the part, "Gabriel go collect 4 crystals, I'll wait here" -- I wanted to shoot myself because of how dated an idea this game is. Expected a lot more from something like Konami with Kojima at the helm.
Another example of shitty game design that makes me rethink my interest in a game -- Enslaved. Watch the gameplay of where you're the dude and you have to "distract" the enemies from shooting at the girl. How do you do this? You

ing shout at them. Really. I though it was cool the first time but the fact that they abused this mechanic as some sort of cool gameplay tool was flat out embarassing.
"HEY ILL SHOUT AT THE GUARDS AGAIN BECAUSE THEN THEY WONT BE ABLE TO SEE YOU RUN ACROSS AN ENTIRE

ING BRIDGE!"
It's the year 2010, how can we still be this stupid? Am I asking for games to be realistic? Of course not -- but when a games breaks the walls of common sense down, I lose practically all immsersion.
It's why running away from guards in Assassin's Creed was so mundane because you
knew you could just turn around and kill everyone one by one.
That's my rant, anyways.