Umm. I just watached this: I'm a bit behind, I know.

Just wanted to comment:

Animation -
Best in the series so far. Fluid, imaginative, truly poo-your-pants awesome.

Artwork -
In my opinion, the physical artwork (by which I mean the landscape, and the water especially) was great. Really great. It was simple, of course, but only to accommodate the action. Too much detail would have detracted from the speed and fludity of the episode as a whole. I prefer the way the water/smoke/fire/cliifs were drawn in this episode to any previous episodes.
I agree, though, that the human artwork left a little to be desired at points, though not all the time..

But it DOESN'T MATTER -the episode was bloody marvellous!