This is some of the best visual design I've seen in any iOS productivity app. Nearly every other "work" product uses a skeuomorphic "list on a sheet of paper" approach or an ultra-chrome, "this is a high-tech product" look. Basecamp has found its own visual voice, which I think works really well.
Interesting. At the latest Rubyconf a few months back the Thunderbolt labs guys stated they didn't think RubyMotion was quite ready for production apps. Perhaps it is now.