For anyone still reading Bleach, last week's chapter (669) showed us, finally, a first look at Kenpachi's bankai.
If you aren't caught up on Bleach, then this is full of spoilers.
First things first, I gotta say that this was a massively underwhelming chapter. 18 pages felt like 4, in true Kubo fashion. Yeah, we did get a money shot of Kenpachi's crazy eyes after transforming, but with the layout of these pages this chapter, we really only saw like 35 seconds of action. Lots of two-panel pages.
This face has officially beaten every other 'shit's about to go down' face in all of anime existence.
From this image of the transformation, we see that his Zanpakuto has actually gotten shorter, and appears broken. Zaraki's appearance changes too, with his skin turning red and his robes becoming more tattered and ragged, similar to Ichigo's fullbring Bankai.
Truly, just before Zaraki SLICES GERARD IN FUCKING HALF, he looks more like an actual demon than he ever has before. He looks tattered and feral, and the ferocity of his attacks signify the same.
It's not exactly what I had in mind for Zaraki's bankai, but it was cool as hell. Hopefully we get to see more of it in a longer chapter.