I actually don't like the dpad for Puyo Puyo Tetris this time around. I kept making accidental fast drops. Other than that, the Pro controller is phenomenal and I use it a lot for Zelda and Binding of Isaac. I'm sure the dpad will be fine for platformers too, but it just hasn't been clicking for me for Tetris the way that the n3DS XL does.
Go to the system settings and check your button inputs on the D-pad, because yours might be defective. At first I thought it was just overly sensitive and easily triggering diagonals and causing the hard drops, but then I discovered my D-pad was actually often triggering up instead of left/right, and that if I specifically tried to trigger diagonals it half the time only actually triggers the up/down component. Some people got D-pads so messed up a direction will trigger the photo capture. Get yours exchanged while you still can.