I have sailed on the Pacific Princess two times, once to Northern Europe and once to Bermuda. I have also siled on the Mercury and the Horizon.
Decor wise, you will find the Pacific Princess 'dated'. That being said, when I sailed on her, she was in great shape, the food and service were excellent. As far as the ride, she was smoother to Bermuda than was the Horizon. The standard cabins are small.
She is a great example of classic cruising. I love her and hope to sail on her again this summer before she is sold off.
Go for it!