It doesn't really matter
As WM6.X shows, functionality doesn't actually matter in the mobile space.
Absolutely everything you can do on an iPhone could be done on WM6.X, and very little changed between 2003 and 6.X (the interface a little).
What matters is how the function (or lack of) is presented, and WP7 does a much better job of that than WM6.X, even if it can't multitask (and as far as I know, WM6 is still the only platform to do it both properly and well, android stutters and falls over running itself, let alone with other things going on).