I'm a big fan of fighting games and enjoy doing combos for really no reason. Just for fun a while ago, I played SF2 for a bit on a 2 button pad to see if I could successfully land a few combos. It was odd getting used to it, but after a while I was able to do things like this Guile combo:
Sonic Boom, whiff Knee Bazooka, stand jab, crouch strong xx Sonic Boom.
Knee Bazooka, done by holding back and hitting medium kick, is useful to approach the other guy while charging up for a Sonic Boom. In this case it lets me continue the combo by following up the projectile while storing a charge to use in the future. It's far from the most complicated SF2 combo, sure, but the important thing is that I was able to use both punches and kicks in tandem while hitting a single button to switch back and forth between them.
That being said, there are many things in the game that are completely impossible due to the limitations of the 2 button controller like this Ken combo:
crouch short, crouch short, stand fierce xx Shoryuken
...due to the need to hit a kick button on the same frame as the standing fierce punch to make that combo work. I was able to get it to happen on a 6 button pad however. From a gameplay standpoint, the PCE version seems quite accurate to me. There are interesting oddities included such as the mechanic allowing aforementioned Ken combo, doing juggle combos on Dhalsim, or hitting an opponent with a redizzy combo.