There's an updated list of Street Fighter 4: Arcade Edition changes over at SRK. I found some of the listed changes intersting.
Hakan can be very scary with his new buffs. Stacking oil will give him the ability to actually stay oiled for a good portion of a round. Hitbox buffs to his F+LP and s.HP will give him some better anti-airs. The ability to combo s.LK into LP Slide (which can then be followed with an oil-up) will help his pressure game tremendously. It's defintely much better than c.LKx3.
Honda is getting well-deserved nerfs. I like the idea that his Headbutt will do less damage from far away. This makes trying to counter random Headbutts less risky. LP Headbutt also loses upper body invincibility, making it far less effective as an anti-air.
Bison's changes are a nice compromise. His s.HK does less damage from a distance, which seems totally fair. His Ultra 2 gets a charge motion, but also does more damage. His super gets complete projectile invincibility, which may or may not come in handy.
T. Hawk can supposedly cancel j.MK into EX Condor Dive, which could make for some interesting mix-ups (or juggles?) His Ultra 2 gets faster startup and better range, which could be a godsend. His Ultra 2 would be awesome if it just reached a little further. I think it has the potential to be more useful than his Ultra 1. Although, none of this matters if T. Hawk remains subpar overall.
Abel gets nerfed really hard. I don't think his Ultra 2 was that scary to begin with, but it sounds like total garbage in AE. His roll is more vulnerable, and his Tornado Throw does less damage. Abel was definitely strong in Super, but I don't know if he was in need of such punishing adjustments.
Dan gets some interesting adjustments, mostly in the way of buffs to the frame advantage on his normals. These buffs give him the ability to do some nice combos via linking. He can do c.LK, c.LK, Koryuken; s.MP, c.MK, EX Dankukyaku; or even counterhit s.MP, Ultra 1.
Gief's EX Glove no longer knocks down, which is something we've heard before. This might totally kill his knockdown mixup game, but will his new in-your-face mixups be even more dangerous? You can apparently steer his Ultra 2 now, although it still probably pales in comparison to "Mother Russia." And in the most unexpected buff category, LP SPD gets more damage and range! I don't think a Gief player could wish for anything better. Jab SPD is already a threat, but this makes it a promise: You will get scooped up! This will help Gief in matches where his opponent is able to poke from further than he currently can really do anything about. I'm looking forward to it.