I only sailed on the anthem for 3 nights, I have sailed on P & O and Cunard as well as Island Escape.
Embarkation was complete in 5 minutes the quickest and easiest I had every experienced, you showed your sea pass to one of the ladies walking around with an I Pad, then straight through security on to the ship, cabins were accessed at 1Pm.
disembarkment was as smooth, everything was very organised on the ship