I like Windows UI logics better than iOS. iPhone is very apps-centric, where in order to get the jobs done, you will need all the apps and all the icons in the home screen. Very cluttered and boring by time. Mango based themselves on information, where in people hub you will get covered in terms of social need (facebook, twitter, chat). Too bad Windows made their apps development so closed compared to Android market.
I have already listed the integration as an advantage of Windows Phone.
And I have listed the apps as an advantage for the iPhone.
With my iPhone, I have just tried about 6 to 8 fitness apps to track weight lifting workouts. Even bought a couple that were junk, because there were not trial versions of some. The one I found best for the iPhone is Fitness Builder. It's not available for Windows Phone.
I don't know if there is a good app to do this for Windows Phone, but it is nice that you can try any Windows Phone app before buying (thinking this was true through the site, correct me if I am wrong). What is nice about the iPhone is that there are more app to accomplish various tasks. If only all had trial versions.
But, I think iPhone users just don't care if they throw a little money away in search of the app that they really want. It didn't bug me too much.
Heck, I even buy songs through iTunes from Shazaam links, even though it is more expensive, because it is more convenient,