There are some severe limitations to the Office infrastructure. For example, I got an ASUS EP121 tablet so I can draw on it. I tried using OneNote as a sketchbook, but when it synced to Skydrive, it made the sketches useless. Needless to say, I can't view them on my phone at all. I just accpeted that it's not what it was designed for.
On the other hand, my son uses it all the time in school. He gets writing projects all the time, like NaNoWriMo last month, and does them all on his Focus S and his laptop, syncing to Skydrive. It works well for him.