Pachinko Kabuto changes his weapon from the Galaxy Slingshot to the Pachinko Kabuto slingshot,. You can fire the Firebird Star without having to use the Save Me, Sogeking! special (SSSST or TTT).
Impact Dial changes his R1 from the crappy little hammer to a punch motion with his right hand, then firing the Impact Dial. It doesn't seem to have block properties like blocking R1 actions have (I.E: Hancock or Ace's R1), so I don't know if it blocks. The shot from Impact Dial has a pretty decent hitbox, makes a nice counter when you see a bunch of peons glowing red ready to jump attack you.
I use Monkeys (Luffy OR Luffy [New World], Garp, Kizaru) and The Reverie (Vivi, World Government, Wapol) in addition to Man from the Island of Snipers. Sogeking as much as possible!
...Heh, I just noticed, his DLC outfit gets a cool Tengu kind of mask instead of the Sogeking mask. Neat.