A few points.
Last year I signed up for the upgrade program for my phone. You made an I store reservation for the phone. Meaning you merely created an appointment time to come into the store to sign up for the program and to pick up your phone.
I reserved a particular color and picked it up after registering but was able to exchange it for another color within a certain number of days. I don't remember the particulars.
This year the process changed a bit. I SIGNED up my WIFE's Phone Line up for the program thru the Apple Store app last night. Yes, ENROLLED her in the program straight from the app. I completed the loan agreement forms and paid by credit card, which was processed. Last year this process of signing the loan agreement and payment had to be done in person in an Apple Store during an appointment.
Also Last night, I was given the option of having the phone shipped to us or picking it up in store.
I chose to pick it up in store as my own phone line has been enrolled in the program since last year's launch and I have to go to a store to return my existing phone in person, in store in order to upgrade to this year's model anyway.