To me, iOS is a bit stale, but has too much going for it... apps, fluidity (more so than Android and BB, at least), user friendly, superior hardware (camera is 2nd to none).
WP is fresh and just does every thing so beautifully. When I pull out my iPhone to use on my commute home, almost every one looks, sees what I'm doing and turn away. With Focus S, I'll see people in the corner of my eyes gawking for extended periods of times, watching all the smooth transitions and seems like they're wondering "WTF is that... that looks cool"