We sailed on the Pride of America around the Hawaiian Islands in October 2013. The attraction for us was the fact that it was an easy way to see Hawaii and POA is the only ship that has this itinerary. As this means there is little or no competition, the price is higher than you would expect to pay for 7 nights on a 4 star ship.
Don't get me wrong, there is nothing really wrong with the ship, but it's not a great 'cruising experience'. We were lucky to be able to afford a suite and I'm so glad we did. Having seen the balcony and inside staterooms I was quite surprised at how small they are. If you have more than 1 suitcase you'll find it difficult to fit yourself and your luggage into those rooms!
I have previously cruised with Princess (twice); P&O out of Australia (never again) and Royal Caribbean. It wouldn't be fair to compare POA with either the Grand or Diamond Princess as that would be like comparing The Cheesecake Factory with a fine dining restaurant, both serve a purpose and cater to a particular market. Having said that, POA did a more than adequate job for what they are designed to do - which is get you from one Hawaiian Island to another.
This is a suite and you get a lot of room and don't feel cramped at all. Be aware though that they publish this as being two bedrooms. It's not. It's one room with a curtain that you can pull across if you choose to do so however there is only a sofa bed in the other 'room' and the TV is right in the middle of the curtain so neither party can watch TV if the curtain is pulled!