I agree with Wallcraft, ePub, Mobi, and FB2 all display nicely on the Pocket Pro. I've completed reading one ePub book and am halfway through one in Mobi and both formats seem to work well, as in neither one caused the unit to crash or hang up.
I've just started using ePub and I'm not sure how I feel about the format yet. The ePub I purchased looked fantastic in some ways - nice oversized caps at the beginning of each chapter and a nicely formatted table. However, the margins were HUGH and I didn't like the default Times Roman Font and there is no way for the user to change these from within the book. I finally dedrm'ed the book and tweeked the master page layout and css files until I got the margins and font the way I liked them. This wasn't hard to do, but it did take time and left me thinking that if I was going to have to dedrm each ePub file I purchased and mess around with it until I got the margin and base font how I like them, I might as well just buy the mobi format and dedrm that. I'm not sure that I'd miss the fancy formatting in most cases.
Amazon will probably end up killing mobi, so I guess I should just learn to love ePub.
