Up and down arrows are equivalent to arrow key behavior, both in the view area and the PageNumberEdit. It also fits better to documents with RTL page layout (mangas) (if there are such documents).
It’s just irritating next to the PageNumberEdit, where “Up” doesn’t mean “Increment Page Number”. (Although scroll wheel “Up” does mean “Increment” there.)
I think up and down is an improvement. Is this also for the tool bar widget?
I already said that i personally don't like it.
Nathan, Andy and David seem to like it (even though none answered about how this works visually when on N columns mode where it doesn't actually move the focused page up/down but left/right)
You can either trust them to know better than me how pretty things look like (which is probably true) or if you want you can try to find more opinions.