Super Street Fighter 4: Arcade Edition was released on December 16th, 2010. The game is available throughout Japan and in a few international locations, including NYC's own Chinatown Fair. Shoryuken has a good index of videos of the new game. Also, this TeamSpooky playlist from CF on Christmas Eve is required viewing — not only for the game footage, but also for Chris Hu's beautiful rendition of "Last Christmas." I posted my hands-on impressions of the game, but here I'll talk more "theory fighter" about what I've observed second-hand via players' reports and gameplay I've seen.
NOTE: The changes listed on the Capcom developers' blog are not comprehensive. There are lots of subtle changes that were not mentioned at all.
Yun is definitely a beast in this game. The number one and number two players in Japan are Yun players, Kindevu and Daigo. Yun can link three consecutive MPs into his upkicks. MP xx Jab Shoulder keep the pressure on blocking opponents. When they get too scared to move, Yun can sneak in a Tenshin (flip-grab). I haven't seen Genei Jin put to good use yet, but his EX moves are definitely potent. The EX Shoulder goes through fireballs and leads to juggles. His EX Lunge Punch is fast and completely safe on block. Tests at Chinatown Fair showed that it couldn't be punished by Chun's reversal Super. His LK Upkicks are perfect for anti-air. His Kobokushi (palm-push) is great for charging meter and has a huge hitbox that even hits cross-ups. The fake palm lets him coax opponents into approaching him. People will learn to deal with many of his new tricks, but he'll probably remain one of AE's best characters.
Yang is also a force in AE. He can keep pressuring opponents with Jab x 3, c.MK, Mantis Slashes. The slashes are apparently safe if stopped on the second hit, after which he can FADC forward. From there, he gets a 50/50 mix-up: He can repeat the sequence or go for a Tenshin. He can easily combo into his Ultra after a MK launch, jump cancel, divekick. I haven't seen any good use of his EX Mantis Slashes, though I'm sure they'll become more prevalent as people learn the character. His Seiei Enbu combo is super simple (c.MK, c.MP, dash, repeat) and does tons of damage. I think that having a Yang rushing toward you will be one of the scariest things in AE.
Sakura was probably the most popular character in Chinatown on the day I went there. She seems to have an easier time pressuring opponents. I don't know if her normals improved or she has better recovery on her specials, but she was definitely more able to rush down (which seems to be a trend in this game). I could be wrong, but her jumping MK seems to have a better hitbox, allowing for more ambiguous cross-ups, like Adon has. She also retains the ability to run away with air Tatsu, unlike Ryu and Akuma. I mistakenly thought that she'd be one to watch out for in Super, but will she realize her potential in AE?
Balrog (Boxer) seems a bit less dangerous. His standing jab whiffs on many (all?) crouching characters now. His close MP is better, but that doesn't have a profound impact. His headbutt does noticeably less damage, and his juggle into Ultra 1 does laughable damage. Also, his headbutt has really bad recovery now. I saw him using it to cross up downed opponents, only to get him by them after they stood up. His go-to ultra may now be his Ultra 2, which is great for stopping pressure tactics, like the twins' divekicks.
Sagat is back to near-vanilla potency. He gets some damage buffs that make him more competitive. He doesn't get back his cancelable LK or his super-safe Tiger Knee, but he is still a good deal better than in Super.
Guy always gave me trouble in Super, and now he's gotten significantly better. His 3-frame low short allows him to keep the pressure on non-stop. He'll definitely have you afraid to push a button once he gets you pinned down. Landing a low short will lead to landing his full target combo (which now hits crouching opponents), which leads to pain. Then he'll run up and start ticking with low short again. Fighting Guy is going to be like fighting Fuerte, a battle to avoid getting knocked down, then mixed up until you're KO'd.
Makoto looks a lot better, mostly due to strengthened normals and a much better Fukiage (DP). She can now combo LP Fukiage after EX Hayate (dash punch) in the corner on most characters. After that, she can combo Tsurugi (air kick). Her EX Karakusa grab is invincible to throws and attacks. She looks to be a really solid rush-down character. Do I see a trend in AE?
Gouken's got some interesting changes that make him better able to fight from close. His quick jab DP makes for nice combos off of jabs. He can now cancel his jumping MP into a Tatsu for some decent damage. Will we see more Gouken players in AE?
Juri can safely use her fireball store on block, which gives you more (you guessed it) pressure ability. I've heard that her EX pinwheel is worse for anti-cross-up, but I've seen it hit behind her. She's supposedly not great in AE, but I'd say that the Juri is still out on her.
Fei Long is just slightly improved from Super, which should make him one of the game's top characters, but Seth seems to be worse than ever.
Rose doesn't seem as bad as everyone's made her out to be. Aside from her Ultra nerf, she seems basically unchanged. If her Ultra 2 is really so bad, maybe a return to Ultra 1 is in order.
Everybody seems kind of down on Cody, though he has some improvements from Super. Once players get a feel for how to use his new low Short, I think he'll be seen as more of a threat.
Dudley is improved in some slight ways, and I think that his F+MK being faster is more significant than most people realize.
Dhalsim seems to do no damage at all, and his B+LK is much less effective now. It was always hard fight from up close, and this certainly doesn't help him. His new DB+MP doesn't add that much to his game, in my opinion.
The Balrog player at Chinatown Fair also used Cammy for a bit. Cammy lost her low Cannon Strike, but she seems to be doing well in spite of that. She can still do the EX Cannon Strike right off the ground and combo for major damage. She's just as dangerous as before; however, she can't rely on spamming divekicks anymore.
There was a Chun-Li player at Chinatown Fair who seemed perfectly comfortable with her. She doesn't seem to have changed much at all. She may do less stun damage and have trouble anti-airing with DF+LK, but otherwise she's the same old Chun.
There were actually two Vega players in Chinatown during the blizzard. Vega seems almost identical to his Super incarnation. Nobody is really abusing his new low MK yet, though I think it will see a lot of use in the future. Also, his DF+HK is noticeably worse on block; it's certainly not worth spamming as much. Other than that, he's not any different.
Fuerte received a few secret buffs not mentioned in the developers' blog. Fuerte's is able to stop his run much faster, and his close HP supposedly has better range. This makes his Run-Stop-Fierce loop easier to do for more reps. Also, his standing MP has more active frames and a better hitbox. Will these secret buffs make up for his nerfed Guacamole Leg Throw and Propeller Tortilla?
Blanka looks a lot better, but I'm not even sure why. I can't tell if his normals got faster or have better hitboxes, but it's clear that he's got more pressure ability. One thing I am sure of: his slide recovers much faster. He lost the ability to ball away at will, but he seems more able to get on the offensive, which is what AE is all about. It looks like he's gone from being a pest to being a menace.
I've mentioned how the changes to Zangief and Abel would affect them prior to launch, and that all seems to hold true. Guile and Honda do way less damage, maybe even to the point of being useless. As for the rest of the cast (Viper, Dan, Ken, Bison, Ibuki, Adon, Gen), I haven't seen enough of them or don't feel qualified to talk about them just yet.