I would say that Ubtunu Touch and Sailfish are the best distros right now, probably on par with very early Android in terms of usability. There are still major issues such as mms being broken, extremely poor battery life in some distros, an embarrassingly bad camera. On top of this, the performance just isn't there yet in most distros, sailfish is the only one with acceptable performance IMO. I wouldn't rely on it for a daily.