Just over 2 weeks ago, Panos Panay referred to the Surface 3 as "the tablet that can replace your laptop". The difference in approach could not be more different. Microsoft and Canonical have obsessed over convergence. Microsoft thinks the same OS and a single piece of glass can replace 2 devices. And while the Surface has improved, it's still not as good as either device on its own.
Canonical, on the other hand, has been working hard to unify the OS, going as far as the display server, in order to allow the same apps to run on different devices by switching between various interfaces depending on the screen size. At its extreme, it would be just one device (your phone), which is powerful enough to drive an external display for a different computing experience. It is pretty exciting. I should know, I was one of the backers of the Ubuntu Edge.
All of this could happen of course. With every year, Intel processors consume less power and run cooler, while ARM chips get more powerful. Even if the march of progress makes such convergence possible, the assumption here is that people would rather own fewer devices, or just one device. As computing becomes more pervasive and the things we do increasingly fall outside traditional 'computing', I'm not sure that's true.
Continuity sidesteps that potential strawman. If I'm doing some research in Safari or working on a document, I can pick up right where I left off on my iPhone or iPad. My phone is charging in the bedroom and I still won't miss a call on my Mac. When Craig Federighi demonstrated continuity on stage, it instinctively felt right. It's how modern technology should behave - by adapting and becoming secondary to people and the things they want to get done.