I got a copy of this controller and I tested it with a friend who is a SF5 pad player (plays on PS4 pad).
Dpad
You can not use the Dpad the same way as a PS4 or traditional Hori Dpad. You have to use it the way that 7L has mentioned. Your thumb has to be in the middle and you roll to the direction you want to move and block. If you tap, the Dpad will get stuck or jammed. If you tap, you might get double input since the Dpad has to move back to neutral. My Dpad has jammed many times when I tap Down-Back. If you roll the Dpad, you will unjam it.
Buttons
Boy, where do I start.
First Problem:
The bumpers are way too big (L1 and R1). This is the same problem that Alioune mentioned. If you try and hit the trigger, you have to be careful so you don't hit the bumper.
Second Problem:
The button does get stuck. I got the pad today and the circle button got stuck many times.
Third Problem:
The R1 button is way too close to the circle button. For MK, that's not really a problem since you just tap the buttons. For Street Fighter, you need to press the 2 mediums to do your V-Skill (Triangle and Circle). Due to the placement of the R1 button, you might get some accidental R1 input buttons. Throws are fine (Square + X) since the Triangle button is far away but the R1 button is way too close to the Circle button.
To be honest, I would stick with the Official DS4 pad instead of this pad. The main problem is not the dpad. You will have to relearn how to use this Dpad or use the Dpad mod (via youtube). The main problem are the buttons on this fightpad. There are no mods to fix the buttons on this fightpad.