I came to WP chiefly because of familiarity with and loyalty to Microsoft, whose desktop and Office Suite products I've used for the entirety of my working career. This business relationship began before any of the earlier iterations of WP, so for much of this time I have maintained a parallel familiarity with an, affinity for and loyal to Blackberry phones and OS, which I still maintain. Blackberry has been a constant and dependable presence in my work and life. BB10 OS continues to be my most favored UI and OS (and I have familiarity also with IOS and Android). But events and the market being what they are, I did begin to explore fallback plans if this dependability should come into serious question in the future. For my needs and preference, it is not enough that my phone be still functioning; I want a device and an OS that will continue to evolve and refine and grow.
Visually, W7 first caught my eye and then interest as an alternative. By now, most of my desktops have migrated to Windows 8.1, so the metro-tile conventions have become increasingly familiar to me, and they held out the promise, in their visual similarity, of greater and more seamless integration with my desktops, my Surface Pro and my laptops. As of now, and in this regard, WP is still more promise than delivery, but I'm hopeful that WP 8.1 will be a great leap forward when its released next year. As of right now, I have better integration with and control of my Microsoft related files and programs with my BB Z30 than I do with my Lumia 1520, notwithstanding the obvious.
My specific excuse to actually get a WP was to evaluate the platform for a partner, but my experience with the 1520 quickly confirmed that for me, WP is a more intuitive, smoother and visually pleasing UI than either Android or IOS. And it really stands apart, as for all my appreciation of BB10, it visually is not all that different than either the way most people set up Android or the way IOS is imposed on its customers. There is an appreciable sense and feel of freshness with WP. It has vast potential. I hope for better integration as WP continues to mature, but there are few other drawbacks for me in using it, and a whole lot to recommend it.