I think that making a multipage form navigation is not so simple as it seems, especially for next/prev buttons. Generally, within a multipage form (for example a cart, but in my case I've got a HUGE 10-pages mega form for made for asking quotations on tech products), you'll likely have a 'page 1 of x' small text, and a probably some kind of breadcrumbs-like indicators/navigators. And finally, the next/prev buttons.
The next/prev buttons won't really work if placed at the beginnings (top) of each slide, because then the user can be fooled into thinking he can go on even if he didn't fill in the following fields.
They won't work as well if placed at the end of the page (at least for me), especially in js-driven multipage forms where one page 'slides' into the other, because you'll end up loosing contact with the button after every click (because each slide will obviously have different height than the others).
So what? How to solve this ux trouble :) ?