We recently returned from a 7 night Alaska cruise on the Island Princess from Vancouver to Seward (Seward is being replaced by Whittier next year). We have sailed on the Magic twice, so found ourselves comparing the two.
The ships themselves are very similar in quality, but the service on the Magic seems to have had a few more smiles. We were on only the fifth sailing of the Island Princess, so the staff may have been still getting used to the ship and to each other.
The embarkation area for the Princess is in Vancouver's Canada Place. While striking from the outside, the waiting area, not accessible until after check in, consisted of crowded folding chairs and concrete floors and nothing to look at. Quite a difference!!
I think the food on the Princess was a bit better in the dining rooms, but Topsiders is far better than the Princess Horizon court buffet. However, the Horizon court buffet is open 24 hours a day. The Princess also has a more extensive room service menu, with meals from the dining room menus available. Our server's name on the Princess was Magic - so if we discussed the Disney ship, our server would hear and hurry over. I really think he should work for Disney.
We liked the Princess public areas a bit better, especially the central atrium which had a spiral staircase, an adjacent lounge,and a string quartet each afternoon. We also thought the evening adult options were better on the Princess. The crowd was not partiularly old and seemed similar to the Magic. We observed very little smoking.
Our cabin was a "mini-suite" which was almost identical to category 4 on the Magic, which we have had both times. The balcony on the Princess was about twice the size of the Magic, allowing a full size dining table. There was no split bathroom, even though the bathroom was large with a full size tub. The cost was about $1800 for each of us ($3600 total).
The cruise was beautiful and we chose it over a third Magic cruise. It was a good choice for a change.