Ars Technica posted a Windows Phone 7 review from an iPhone user's perspective

Like many of the other staff at Ars, I've gone through a couple iterations of iOS, and watched it mature into a more functional, more usable product. In the last few months, I've also gotten the chance to play with what are essentially 1.0 versions of smartphone operating systems, Windows Phone 7 and the newest Blackberry OS, both of which are intended to be touchscreen-ready and radical departures from their predecessors. Having sampled both, I think it's fair to say that Microsoft did a fantastic job compared to RIM, but it still has its work cut out for it, and may need to rethink some of its interface choices.

  Windows Phone 7 from an iPhone user's perspective