Thanks for taking the time to list those. My initial reaction to each as it relates to me, as a prospective smartphone buyer:
1) "Better UI" seems pretty subjective given that there isn't a consensus pick among smartphone users of existing interfaces (anecdotally, it seems that it's whatever the particular user is used to using).
2) This isn't really an issue for iPhones and BB's. It has been an issue with some of the lesser Droid phones (simple solution for users being don't buy a cheap smartphone--which I wouldn't, if I were going to get a smartphone).
3) I personally don't own an XBOX and couldn't care less about this.
4) Aren't there Droid apps that deliver a solid MP3 player?
5) I do agree that lack of Flash support is a major drawback of iOS and BB.
6) Every smartphone OS on the market right now that I know of (Android, iOS, BB, webOS) supports MSFT ActiveSync. What will WP7 be able to do that these others can't?
7) This is probably more of a key feature for users who are apprehensive for storing files in a cloud service, like Dropbox.
On whole, I see the potential for it to compete fiercely with BB for corporate users (particularly if there features of MSFT Exchange that can only be utilized by the WP7). But, aside from the XBOX Live (which has limited appeal, IMHO), I'm not seeing very much that it offers consumers that isn't already available from at least one of the existing smartphone platforms.