I didn't find it to be any different personally, I think after DMC 3 the guns actually needed a serious tone down, I, and I'm sure that others, found that in a lot of respects, they were more powerful than some Devil Arms.
I still find Gunslinger to be extremely useful, the Shotgun's Stinger technique was a new twist that I appreciated, along with the Missile Platform of Pandora, even Omen was stupidly powerful, then you've still got Ebony & Ivory, going strong with Twosome Time, able to fend off quite a large amount of Demons, then mixing that with Honeycomb Fire to finish them off.
Really, DMC4's Gunslinger style was one of the only things I enjoyed about the game, it was intuitive, forced you to think fast if you planned on relying on it and it wasn't too powerful.