Well, heres a brief rundown, i'm still pretty early
* Touch screen everything - movement, selecting, everything
* Battle Music is nice. Reminds me of Legend of Legaia
* Battles are gay. they're turn-based... but more "round-based" - everyone does their attacks then its Round 2, repeat. it's kind of semi-auto? sort of like Phantasy Star's programmable auto mode, for the Genesis.
* You gain levels, but you dont do stats lke other BioWare games. you can add like 1 or 2 bonus points to a stat, otherwise its natural growth.
* You can choose your responses, but they dont affect "good/evil" stuff
* Enemies are on screen, no random battles
* There are Chaos (little blue things), you can equip them for little effects. you can trade with friends (not via wifi though), i dunno how else to make them grow.
* There's a Codex, tells about Sonic's world, and other random BioWare shit that they introduce
* Story is that Sonic & Co. defeated Robotnik FOR THE LAST TIME, and Robotnick is gone. But theres this weird race called Marauders, that stole the Chaos Emeralds, and kidnapped Knuckles. Sonic comes back, was away for a long time apparently (Tales references this). For some reaso Robotnik's robots are acting weird and attacking, so they think Robotnik is back...
* Loading screen when switching areas
* Cutscene intro movie, etc
* Graphics are nasty, of course, models have that "cel shade" look
* Item descriptions dont show up in battle, so you have to basically remember what item does what
* You move around with the touch screen, and then little icons appear that you have to tap (or press L/R). Switch characters to do different effects (Amy smashes things, Tails flies, Sonic does fast loop de loops, Knuckles climbs, etc)
* You can save anywhere