So I just "purchased" this port of Sonic the Hedgehog (titled "Sonic 1" on the iPhone menu, so expect more) and I have to say, compared to some of the other ports out there, it's pretty top notch. It controls surprisingly well, and runs fine. If any of you guys have an iPhone or iPod Touch, you should check it out.
As an added note, the virtual d-pad earns bonus points for looking like Genesis buttons.