My wife and I just completed our second Australia-New Zealand cruise with Princess. One year ago we sailed on the Sapphire and this year we just completed a cruise was on her sister ship the Diamond.
I am in a wheelchair so my comments will pertain in certain instances to the facilities on board that either contributed or failed [none!] to contribute to the pleasure of the voyage.
Last year the embarkation was pretty much a "dog's breakfast" but this year we had no trouble during any of the embarkation formalities. All went smoothly and that perhaps was because we stayed several nights in Auckland before embarkation.