Oh ... Window's phone ... I forgot they existed ... I have an android and the evil iPhone (work phone). I have the app for both. Not a bad tool I guess. But with the need to ask for upgrades instead of getting them automatically, the check-in is actually useless since we still need to talk to someone at the desk.
Keep in mind, even if you see you have an upgrade on the phone, that doesn't mean that you will still get it when you check-in. Yes, I have had that happen several time.
With that said, I hope they get it for you soon! It is a nice way to speed up the check-in process and monitor your reservations.