I have a Samsung Focus on Rogers (carrier in Canada), and with what I thought was moderate data usage (a lot of emails, bunch of apps downloads and updates, extensive internet browsing, without any youtube though) I merely got over 200MB of my 500MB plan. I would blame that the guy uses netflix or youtube a lot. That or AT&T's legendary bad network.
Looks like this is the Windows Vista phone noone wanted!
MS is known for using all the hardware to 'optimize' the user experience, instead of keeping it simple, and reduce background traffic.
I'm only interested in a windows phone if it has a usb port, stereo mini jack out, and can load/run any normal windows 9x/xp program.
-.- I have a Samsung Focus and have only used 30mb of my 200mb this month
On a side note,
This phone is really amazing and all of you naysayers will eat your words sooner or later. Lol how many of you have even tried a wp7? Just saying, I hated on iPods until I tried one.