My 1 and biggest complaint about WP is the relative inability to be able to load files onto the device. For years I was able to create files with Word, Excel, etc and send them to my iPaq and later my Axims and the file would sync and convert back and forth between device and PC effortlessly with no problems. I could create it on my computer, take it with me, edit it when away and return it back to the computer for other addendum's. I could move photos or any other item as needed and there wasn't any problem. It was nearly like a true handheld computer.
WP? Not so much. I just can't understand why you have a device/OS that's written to represent a software company that creates the OS that many use on their home computer and it cannot easily communicate with each other. When Win8 comes out and WP8 come out, will there be any ability for cross communication or will it just be another version of Zune? MS doesn't even really support the Zune Players anymore so why is it so important to look at the new WP7/WP8 devices as a Zune player that happens to be a phone also? Just because it worked for Apples marketing, doesn't mean it'll work here.
OK, I'll stop before this becomes a rant. I do like my Arrive and appreciate how well WP7 works compared to the slowness of the older WM devices