Overall impression: The Island Princess is a fine ship--it is in great shape--looks almost new. The ports and glaciers--this ship goes to both Glacier Bay and College Fiord which is a great combination--you will see multiple glaciers. Other ports are standard--Skagway is OK (I prefer Sitka)(I rented a car instead of the train and drove into the Yukon--Whitehorse was surprising nice), Juneau is fine, and Ketchikan is pleasant (ps in Ketchikan you can walk 10 minutes to the Safeway if you want to buy anything and the store even has free internet access).
Re the Island Princess--the ocean view cabin is small--it isnt small by measurement compared to other ocean view cabins on other cruise lines--but due to what I regard as a poor layout due to the wasted space for the "walk in closet" and the wall running perpendicular to the orientation of the room which cuts the room by 1/3 and makes the bed area seem small--not even enough space for a small couch. You will feel cramped. I am sure Princess did a lot of research on how to arrange the space--but I think it makes the room feel cramped. And the comments on the shower that other people have commented on--it is really tiny--if you are at all a bigger person (really I am normal weight (BMI 24...) and it was tight)--it will be tight--seriously--you will be surprised how small it is.
Re the layout of the ship itself--this is great--if you like to walk--you can walk on the promenade deck or the top of the ship. The lowest level, the Plaza--does feel claustrophobic as it opens to the atrium. And the coffee shop is on the Plaza level along with the dining room. Get the coffee card for around 32 dollars and you are set--just leave your room and get endless brewed coffee and up to 15 expresso drinks--right there near the room--no need to go to the Lido deck. Re dining--never a signif wait for a table under anytime dining. Service excellent. The food is fine--as long as you stay with pure american or italian food. Anything non-european will be terrible--interestingly, Carnival or Holland America do good Asian food--but not Princess. The italian food on Princess is good--surprising good pizza. Food was fine, both on the Lido deck, and the dining room.
Overall a fine experience.
I rented a car--split it with another group of 2 people. Net cost including gas was around 180 dollars--so 45 per person. Much less money then the train. Whitehorse was nice--great bakery on the main street.