I've been using Eagle on Ubuntu for years with no trouble. Bluesam, what kind of visual problems are you having? Is the problem on-screen or when you print? If on-screen, can you post a screenshot? I seem to recall having to preload a library or set an environment variable to get Eagle to play nicely with GTK themes but I don't think that's required anymore.
As long as printing is set up correctly there shouldn't be any problem using Eagle under Ubuntu. . .at least, not in my experience.
i've used kicad and eagle on linux, no problem but I don't really like either - they worked fine though.
Currently use DesignSpark and Cadstar
Have (fairly recently) used Altium designer, orcad layout/capture, pads, expedition, eagle, freepcb