According to this Destructoid piece, the Street Fighter hardcore are complaining that the apparently brilliant Mad Catz SFIV stick... sticks.
Members of the Shoryuken message board are complaining the joystick sticks in its former diagonal position instead of snapping back to the neutral zone.
This is all about the lower cost stick, for the record. There's a beefier version which is apparently "perfect," as we've just been told.
There's no geek like a Street Fighter geek. Full thing through there.