I was looking at new phones just before Christmas and a couple things about iPhones bothered me...1)network coverage in Iowa 2)speed of the data network 3) harder to replace battery 4)Apple is very proprietary, so you better like it out of the box. third-party apps running in Safari may happen, but going to be a dissapointment i think.
Instead I stayed with Sprint and purchased an HTC Touch. Runs Windows Media 6.0, has storage capability of an iPhone, much better network coverae and data speeds from what I have heard. Tons of 3rd party apps, skins, etc. to purchase, some decent ones are free, or you can develop your own.
That being said, the iPhone is probably simpler, does look great, and easier to operate. A WM device allows for more tweaking, but the possibilities are endless...imo