You dont need to be eligible for an "upgrade", the phone comes out Friday at 6. The treo especially (dunno about other WM phones) has a smaller screen, I dont believe it has wifi, and is not as good of a media player.
You guys can hate on it all you want, but this looks nicer aesthetically, has a nicer user interface, and is a better media player than what is available. Even the internet is better on it, no its not as good as a laptop due to the lack of flash but it is better than whats available on most phones.