Ok, here goes.....I was on the Carnival Tropicale, years ago. It was in my view, a dirty ship, with a crew that left a lot to be desired. After that ship I said, I was not going to sail an older ship again, and I haven't.
I guess I would say..you alone know yourself, and how things, such as how Beenie described in her review of the Triumph would bother you, or not bother you. The price reflects the fact that she is an older lady in need of a makeover.
For many, the ambiance of a ship is all important, and others will realize that the great price they got, will allow for more cruises in the future, and overlook, and understand, the ship needs a refurb.
Please don't get me wrong, we had a ball on the Tropicale, we met great people, and sailed a wonderful itinerary, and enjoyed it, and indeed the price was lower. I do look at prices when I book, but I stay away from the older ships now because of MY experience. No doubt you will enjoy a good cruise...
Last month I was on the Conquest, and it was a great cruise, so don't count Carnival out...sail the Triumph with a smile, and next time give RCI a try, and compare. As Dina mentioned, there is always a newer, bigger, flashier ship on the horizon Make your decisions, that are best for you.