This video shows a couple of combos in SSF4 for Makoto, Dudley, Juri, Sagat, Gouken, Ibuki, Chun Li and Dan.
My thoughts:
Makoto: It is now confirmed you can juggle after her 2nd Ultra just like in SF3 TS, but the combos are a little different. She has insane damage with her 1st Ultra to a known high right now of 602. Hopefully getting in will be easy.
Dudley: The new Rufus due to the many combos for his 2nd Ultra. The damage on most of them looks good and his damage is ridiculous overall.
Juri: Her 1st one seems good but getting a hit after initiating it will be difficult. Waiting for an infinite with her lol.
Sagat: His damage in that combo was sad. Not a really bad thing since he was overpowered, but now he does the same amount as Ryu's classic ultra combo did in SF4.
Gouken: Seems good but charging will be tricky. There are probably many more combos with his Ultra 2.
Ibuki: New Viper I say, that Super combo is amazing and the damage on that was ridiculous. She's gonna be good.
Chun Li: Her new Ultra is sick. Supposedly it'll always hit 20 hit in her combos.
Dan: I'm actually impressed with Dan now. Seeing that combo and the damage he did he has potential of seeing beyond the shit tier.