Don't take this as condescention. I'm cheering for Microsoft on this one. They need a good mobile device in their lineup. But if you're ready to buy a Windows Phone 7 device on day one...why?
There are plenty of reasons to avoid a WP7 unit—it's a first-generation product; it lacks some basic features like cut-and-paste (although that's coming); other mobile operating systems are more advanced—but I think I understand those differences pretty well.
What I'm curious about is why those of you who are getting ready to plunk down some real money for a WP7 unit are excited about. Help me relieve some of my own ignorance.
If it were me, I'd guess the integration of Xbox Live could be a big selling point. I'm a little too much of a cross-platform gamer for that to be a tipping point, but for hard core XBL players, I can see the connection. But I'm putting words in your mouth.