Got my FC through from Samurai Ghost yesterday (thankyou!), and couldn't resist plugging it in for a game of Street Fighter II. I like it, a lot, but it's noticably smaller than the Avenue in your hand. I haven't actually compared it to a SNES pad yet.
Overall though I'm finding the pad is really responsive, and though it seems loose (quite a lot of give around the x/y axis) it really sticks to your thumb, and the height on the z axis is just about spot-on. Same with the 6 face buttons.
For some reason though, I'm finding it unusually hard to pull off dragon punches. What's everyone elses opinion?