[Zek]

What people seem to be missing here is that Naruto appears to have gained a tremendous amount of speed. Sure he's not shown with blurry-lines or whatever, but think about how fast Kakuzu was relative to the other members of the group. Usually when Naruto pulls off a surprise move like this against someone that's faster than him, they're able to just counter it anyway - for example, see Chapter 192. The fact that Kakuzu never even had a chance to turn around is proof that Naruto could match his speed, which is a pretty substantial improvement from before.

I agree though that this new jutsu is sort of disappointing. Sure it's basically an instakill(we better not see anyone that's capable of surviving this) compared to the almost-insta-kill of the Rasengan, but he hasn't improved its delivery in the slightest - in fact, he now needs two clones to prepare it instead of one, and that's assuming he still hasn't learned to do a regular one one-handed.

Also, something that occurred to me: the incredibly flashy delivery of this attack makes me think that we probably won't ever see it again. Either it will be condensed into a single double-page explosion next time, or he'll have developed it further to make it interesting again by the time he hits somebody else with it(or he'll miss with this version a couple times before then). Kishimoto doesn't like to re-use these big flashy attacks very much.