I have a Windows 6.5 HTC Tilt2 phone that I really like.  Use Farm Trac to keep field records.  I add the records to the phone during the day and download them at night to a desktop that has Farmworks loaded on it.  Sure beats pencil and paper.  I got checked for my spray record two years ago and the lady said they were the best records she has seen.  It works pretty slick without too much trouble.

Only thing about the windows phone is they have very few apps compared to the Iphone or the androids.  Hopefully now that Windows 7 is out more apps will be developed for it.