I doubt I would when it first came out. I'm quite happy with Windows Phone. What I will say though, is that if I were to leave Windows Phone, I'd probably be more likely to go to Ubuntu than I would Android or iOS.
Ubuntu is a great desktop Linux OS and from what I've seen, the phone OS has great potential. I hope Microsoft is paying attention to it too, and not afraid to copy some good ideas. I think Windows Phone could use a bit more for the "power users". Not taking away from the simplicity of course, but more under the hood than we have now. Ubuntu and BB10 seem to be prepared to deliver that, so my hope is that Microsoft will follow their lead and WP 8.5 or WP 9 will have some more robust features.
I think they will have a hard time getting it to take off though. As nice as Ubuntu is, I've been listening to Canonical make promises about Ubuntu really taking off in the desktop world for a while and I haven't seen it materialize yet. Most OEM's are just too afraid to commit to it, which is a shame, because it's quite good and the world deserves more choice than just Windows and Mac OS X. There is no good reason why Linux couldn't been that third option and Ubuntu is the most user-friendly desktop Linux you'll ever see. Forget about dependencies and having to type arcane commands in the terminal. My 66 year old mom could use Ubuntu with no problem.
Anyway, I'll be watching them closely on the phone.