Ironically enough, I've never ever had any problems with setting up a rails stack in Debian. Not my cup of tea distro, but some people I work with swear by it. I guess it has to do with all the stuff I do and preset when creating an image to base servers of.

Nevertheless, I've found Ruby and Rails easy to install in any machine I've tried them in (A LOT), and I guess that for less Unix inclined users it might get a bit complicated along the way.