reservation
I have the feeling that the United app at this point only works if you have an active or recent reservation.
I couldn't get it to load for weeks and weeks, then when I had an upcoming flight in a few days, sure enough the app loaded. It worked till 1 day after my final flight landed, then it stopped loading. I think it is doing maybe SOME sort of validation with the iphone app.
Also, it doesn't do ANYTHING more than show current reservation/s and flight status for the current flights in your current reservations. So, it's not a great loss to not have it do anything.
I DID use it to check-in at the gate (actually used passbook on the watch) and it's nice that when displaying notifications for passbook items, the screen doesn't time out quickly or go dark when you tilt your wrist.