You know, when I first got my Z Ultra I figured I should get one of these. I ultimately didn't because of the price; It's expensive as hell, and as much as I like the battery cases, this does have the one grand feature of being the only flip case I've seen that doesn't block the damn micro-USB port when it's closed.
I've seen leather cases for it for markedly less, and the delivery fees from this are insane- it's actually more than Sony's CP12. But, it's by far the highest quality case, and Noreve has a good history about it.
It's really the way to go if you absolutely have to have the absolute best quality.