I tried out the new manga features on the free
Shonen Jump Manga Starter Pack. I can see why they released a manga kindle model with more storage. This sampler used over 100MB of storage on my Paperwhite 2.
The fast page change using press and hold works pretty well, much faster than I expected. (It's odd that multi-thumbnail page flip isn't also supported for manga. It would be useful for finding your place in a book with visual pages like those.)
I found the pinch zoom to be OK, but not great. (I would prefer a panel-by-panel mode, but perhaps the visual layout doesn't lend itself to that.)