I installed XDAndoid to get familiar with the OS. I also installed MSKip's SPB MS based WM7 theme - by most accounts, it's somewhat close to some basic WM functionality, at least as far as live tiles are concerned.
I really like the WM7 interface. Much more than Android. Seems to be very useful in getting lots of info and access to most used function right on the home screen while being finger-friendly and decent looking (although with no customization, the Tiles look can get boring soon).
If I had to pick today, with all other things being equal, I'd get WP7 over Android. However, it also depends on what options Sprint has a year from now (if Sprint is still around a year from now
). If the $50 Optimus S was available when I got my $200 TP2, I'd get it instead - it still gives a typical smartphone experience at $150 less. So, I will wait and see... but at this point, WP surely looks good. Unfortunately, the memory consumption of W7 theme is so high, I am back to Titanium.