On my Macbook I've tried many many coding fonts, yet Ubuntu Mono is actually the best. All others either seem to render weird to me or I don't like their look in the first place.
One reason I like Ubuntu Mono is that it supports a large number of Unicode characters. When I was using Inconsolata, a non-ASCII character would be replaced with a glyph from a different font (usually being a bit too big in gnome-terminal). I'm glad that there's a variety of high-quality open fonts to choose from!
The biggest problem with Ubuntu Mono is the rather small size of its punctuation, especially dots have been nearly invisible for me. Other than that, the Ubuntu family of fonts are fine indeed.
Ubuntu mono always seemed a bit crowded to me, it was my default before I got my hands on Consolas. With infinality freetype it looks really beautiful too.