Calibre?
I've not yet used the sony supplied software with my PRS-350. The open source calibre program (http://calibre-ebook.com/) had no difficulty putting drm-free pdf files on the unit, so whilst you may not be able to simply drag and drop pdf files there is a way to manage it without the obnoxious sony/adobe software.
It's also been on offer at £130 from Waterstones since it was released, only £21 more expensive than the cheapest kindle. I think that's well worth it for the better build quality and touch screen.