The Ubuntu mobile UI was a nice platform to work with in a tablet or phone interface, but the application ecosystem was horrifying to deal with. I am sorry a slapped together wrapper for someone's website is not an app. It is a bastardized browser experience that is worse than just using a browser. And combine that with no core applications aside from the ones developed by the OS team. Its death is not surprising, but it did make me sad.
Convergence so far has never been approached well. the closest I saw was The Ubuntu Mobile experience, but It relied on USB video and experience too much to ever become what it could have been. I think just creating a secure data exchange between desktop and laptop so that your mobile devices becomes a "Userspace" mirror would be far more valuable. then build applications that are specific to each physical platform that can then interact with that communal data would be a success. so far nobody has really embraced that.