I don't think it will be a threat to Windows Phone or anything else. As was said, its going to be a niche product. Much like Sailfish, the reborn Meego OS, it's a niche product without much of a niche. Few are going to want a phone OS with virtually no support from the outside world and few mainstream apps to choose from. Windows Phone has a hard time as it is gaining new users and it's hardly a niche product.
Originally Posted by nbktonic
That said, I am a fan of Ubuntu and I like the idea of a real Linux phone running native apps instead of a Linux offshoot running Java apps through a virtual machine (Android) which I've always seen as an imperfect solution.
I also think the Ubuntu phone OS shows some real ingenuity in the UI design, so does Sailfish. Even though I don't think either of them is going to catch on, I think Microsoft should be paying close attention.
One of the biggest reasons I love Windows Phone is because Microsoft did a very un-Microsoft thing with it. They decided to color outside the lines, to abandon the traditional grid of icons motif and conventional UI design. They began from the ground up and designed the first smartphone OS that is truly user-centric instead of an app-centric. I think the significance of that can't be overstated, in fact I think most of the time people who just review Windows Phone or don't use it, miss that subtle, but key attribute that makes Windows Phone truly different. It doesn't just look different, it WORKS different and that makes it more pleasing to use in many ways than the typical smartphone which just feels like a launcher for a bunch of disparate apps. Canonical clearly saw the brilliance of that concept because they are applying it in their own way to the Ubuntu phone OS.
The reason I think Microsoft should be paying close attention to Ubuntu and Sailfish is because that is the real future of the smartphone. Something that is greater than the some of its parts. Whereas iOS and Android are the past of the smartphone. My hope is that Microsoft will continue to be brave enough to keep thinking outside the box. I'd hate to see Windows Phone just stay where it is, making only incremental improvements to the original concept.
Stick to the elegant simplicity idea, but don't be afraid to add capabilities for more advanced users and don't be afraid to keep pushing the envelope with the way the UI functions. In particular think the gestures idea and the way in which multitasking works in the Ubuntu phone and Blackberry 10 are things Microsoft should seriously consider in designing the next major revision of Windows Phone. I think that differentiation, smart differentiation through better design, not just merely looking different, is the key to Windows Phone's future growth.