*Disclaimer* This is not intended to start a flame war. I'm simply offering my views for discussion.
First off, I need to say that the Arrive is a very well done phone. HTC really knocked it out of the park, in designing this phone, aside from minor design flaws (volume rocker design is too wide and catches on the battery lid). Microsoft really delivered a much better OS than most thought. Considering how atrocious Windows Mobile was, the bar wasn't very high to begin with. That said, they still delivered a very promising OS, that will only get better with time. The Zune and XBOX integration almost convinced me to keep this phone, because it blows Android (media management and gaming) out of the water.
In almost every way the Arrive would be a perfect phone for me, with the exception of two things:
I own the EVO as well, and though these phones share similar internal hardware (same Processor and Adreno 200 graphics), the EVO wins because of the huge 4.3 inch screen and the fact that it runs 4G. Call me a n.e.r.d., but I simply don't believe in a "smartphone" tax for a 3G device. If I have to pay the tax, I'm going to get a device that will take advantage of it. 3G does NOT allow for a "premium" experience, in my opinion. For those that don't care about screen size or have access to 4G, then the Arrive is a great device, and I highly recommend you to try it. The OS is very easy to use and the media management and games are great.
I'm hoping that Sprint will eventually announce a 4G version of the HD7s (with a Super LCD screen) Windows Phone, because that would fit all of my needs perfectly. When this happens, I will gladly jump back onto the Windows Phone bandwagon.