Our experience has been excellent. My wife and I each have MDX accounts and, while still at home, we linked the will-call confirmation number for our Premium Annual Passes to our accounts. When we arrived in WDW this past Thursday, we went to the Guest Relations at Hollywood Studios to activate our PAPs. There were about 6-7 people in the line in front of us. We were in line for about a minute when a Cast Member walked by the line and asked if there was anything he could do to help. When we told him we were in line to activate our PAPs on our MagicBands, he said a regular will-call ticket booth could do that for us. The CM walked us to a regular will-call booth where another CM helped us right away with no waiting. We gave the CM our will-call confirmation number and our three sets of MagicBands (we have three segments during our 15-day stay). He linked the PAPs to all three sets of MagicBands. The entire process took less than 10 minutes. We haven't had any problems using the MagicBands to get into the Parks, to manage our FP+ selections, or to get into our rooms. I keep waiting to encounter a problem with our MagicBands, but so far so good. One thing to add: When we moved from the Art of Animation to Bay Lake Tower, the CM at BLT made sure we were checked out of AoA before she checked us into BLT. Also, I have the feeling that the CMs are still learning how the MBs work. They frequently preface their answers to our questions by saying "Its suppose to work like this" or "We think its suppose to be done this way." To sum up: If the only thing you need to do is activate a PAP with a will-call number and link it to the MagicBand, you can go to any will-call ticket booth at a Park. You don't need to stand in line at Guest Relations. BTW: We also intended to buy a Tables in Wonderland card when we activated our PAPs. Of course, that can't be done at a regular will-call ticket booth. Since we weren't planning on needing the TiW right away, we waited until we left Hollywood Studios to stop by Guest Relations to buy the TiW card.