Why does there have to be "one device to rukle them all"?
Look, I'll admit that I'll be thrilled if / when I have a single device that does EVERYTHING that I can imagine, from being a pocketable phone with passable web browsing and e-mail, right up to a full immersive 3D gaming platform and "content creation" workstation - but I think we're still a way off yet.
My current mix is a phone (Nexus 4), a compact tablet (Nexus 7 2013, with a compact Bluetooth keyboard for those increasingly rare occasions when touch-screen typing just isn't "good enough"), and a 15" Windows 7 notebook (with a full-size keyboard, mouse and a secondary 22" monitor when I'm at my desk), which is my machine for doing "real work". Interestingly, this machine spends an awful lot of time gathering dust these days - because it turns out that most of the time, I just don't really NEED a full-on heavy-duty content-creation workstation! It's actually a bit too big and cumbersome for everything other than really serious work - it's become more of a desktop-replacement machine than a true portable device, especially since I got a tablet that does most of what I want. I'm contemplating moving over to something much more compact (such as a Chromebook or similar) for this "mobile desktop" work.
I'm afraid Microsoft has pretty much missed the boat on mobile computing for me - they haven't noticed that for many people, something that is compact and cheap (or better yet, free), and "good enough" meets most of their needs. Microsoft want me to buy a subscription to MS-Office 365, but I'm sorry - for my limited requirements for truly mobile computing, the cheap / free alternatives (Docs to Go, Quickoffice, etc) on an affordable tablet are plenty good enough - both with respect to the somewhat restricted feature set of these "Mobile Office " software packages, and the general limitations of mobile devices compared to "proper" computers. When it comes to "mobile computing", the mobility, convenience, and low cost are more important than 100% MS-Office compatibility and functionality.