I can honestly say that after my experience with windows mobile 6.1 I would not touch this with a bargepole.
I would only consider WP7s if there was a beta rom I could install onto my phone - there is no way i'd like to get lumbered with an 18 month contract on this OS.
I do hate the device manuufacturer stranglehold on the OS roms, why can't MS control this aspect of the phone and force the device manufacturers to concentrate on supporting their hardware rather than buggering up the OS