Couldn't agree more with all that's being said here. Coming from the iPhone platfform which has a magnificent (and free) eBook reader called Stanza and encountering the N900 PDF reader makes for a painful experience.

Might be worthwhile voting for the related "bugs" below which already have a fair few votes - more can only be better...

761 Please add support for 'fit visible' option to PDF reader
2150 PDF Reader doesn't support internal document hyperlinks
5921 Provide portrait mode for the PDF reader application
5923 Add PDF index support