Block back or button
I reckon the difference is a simple matter of preference. Personally I never really got into SF back in the day, preferring my side-scroller brawlers like Streets of Rage at the time, but really got into fighters with Virtua Fighter, so to me using a button to block has always felt more natural, and I appreciate the ability to block while standing still, but I guess it's down to what you're used to.
So it seems as if this might be a return to form for the series. I adored the first game (ignoring Soul Edge for the moment) on the Dreamcast, although to be fair that was as much due to its visual prowess on the little grey box than it's fighting engine. I also enjoyed the second game on the then next-gen machines, but I didn't put the same number of hours in as the sublime VF4 had already been released on those consoles. Since then VF4Evo and VF5 have fulfilled my fighting needs, alongside the odd foray into the DoA and SF3/4 universes, and Soul Calibur has joined the other Namco fighter (which I shall not sully this post by naming) in my 'never in a month of sundays' gaming box.