I have played and completed the demo, actual CHILLS. The graphics are unbelievable, the depth of character form people like Jesse, Biggs and Wedge is fantastic (this was one of my gripes about the original, I didn't really care when they died fighting under the plate). The battle system is different but certainly more exciting - it didn't take me long to work it out at all. I love how they've changed some of the dialog to start fleshing out Cloud from the start, not a massive fan of Barrett's 'Mr T' voice but he's a little less 'gangsta rapper' than he was in advent children.
The camera situation was weird but after messing with the settings I fixed it so it would follow me rather than me having to readjust.
My only criticism? I have to wait another 4 weeks for the full game.