Part of what makes or breaks an operating system is the font. When Google revealed Android 4.0 (Ice Cream Sandwich), they also showed off a new default font.
Roboto has had it’s fair share of criticism, put has it’s fans as well. I personally really like it, it very simple but looks good in almost any environment. I’m currently running an ICS ROM, and the font really makes texting and browsing the contacts a much more pleasurable experience.