The progress on Servo is impressive. UI polish is required in order to be more usable. Things like keyboard shortcuts to focus the address bar are required to make it feasible for more daily driving use
i've been hacking on my own browser using servo as a library! its lovely to interface with.
My understanding is that the main focus is on the engine and building a good embedding API so that folks can build browsers (and apps and web drivers etc...) with it.