We have cruised on the Mardi Gras five times and the Celebration twice.
There are so many positives to the Excel class, I think you should book it and decide for yourself.
We loved all of the dining and bar offerings, you literally could eat at a different place every day and still likely miss something.
There are a ton of activities, and the ships are high energy.
The Serenity area on both ships are beautiful and spacious.
The staterooms are more modern. Some complain about the size of the bathrooms, but most rave about the generous size of the showers. Our recommendation is to go with the extended balcony category.
The shows and talent are so much better than on the older ships.
Because at times we are laid back cruisers and sometimes just want to chill, we are now alternating between the smaller ships sailing from our home port (Tampa) and the Excel class.