I was in WDW over Columbus Day weekend. I had purchased regular APs with a
DVC discount online in the Spring before the prices went up (not a renewal). So I had a Will Call receipt I printed from Disney's website, not a paper voucher. I had a little trouble linking it so I could participate in the FP+ test with Magic Bands, but I finally scanned the barcode with my iPhone from the
MDE app and it worked great. I assigned the APs to the appropriate people, made FP+ reservations, and just hoped for the best. On the first day we planned to go to a park, I arrived before rope drop at MK and went directly to Guest Relations. The wait was around 10-15 min at this point. I handed the CM my Will Call receipt, explained I needed to have my APs activated and linked to my MBs. She first issued me the hard plastic APs so we could get our discounts, etc then spent a few minutes at her computer making sure the bands were linked correctly. I was a little worried because I came early by myself and only had my MB, but she was able to get everything linked properly without the other MB even being there.
It took a total of about 20 - 25min. Our MBs worked as a room key, for room charges, for FP+, and entrance into the park for the whole trip without incident.
I realize my experience may not be typical, but I actually enjoyed the whole system very much. I wasn't sure if I would like it, but it was very convenient.
My advise is to come prepared and expect a few glitches.