Having played Sly 1, 2 & 3 I breezed through the Playable Demo, it was fun & i can't want to Play Sly 4 in Feb 2013!
I too think at least one, if not two of the voices has changed, they just sound different, I suppose I'll get used to them though.
I'm a HUGE Sly fan. The original 3 PS2 games were my childhood
Glad you like the demo
Oh, by the way, Sly's voice actor is the same as previous games. His name is Kevin Miller