(This will be a long review, sorry) We went on this cruise with another couple, booked through a travel agent in his home town. We originally booked the lowest level balcony, but Carnival offered an upgrade sale that we took advantage of to get closer to their suite on Deck 9. It's nice up there by the bridge.
We stayed 3 nights in San Juan prior to the cruise, and really enjoyed our time there. On Sunday afternoon, we headed to the port about 3PM to embark. The lines moved quickly and we were on the ship within 30 minutes of arrival.
We found our cabin (9207) easily - standard balcony cabin, but one thing Carnival has done well is to create space with lots of storage and a comfortable room. Cabin steward Denik did a great job, and even got me a longer extension cord for my CPAP machine (the one I brought did not have a long enough cord). His service was professional and unobtrusive.
Nice cabin, very quiet, close to the bridge. You can go up one flight to Deck 10 forward to an outside deck with a great view and wings over the sides of the ship to help the Captain dock the ship. Great at night for stargazing.
Lots of room for storage, the balcony dividers can be opened if you're traveling with friends in the next cabin, creates an illusion of more space. The bed was OK, but bring a long extension cord if you need a CPAP machine. A power strip enhances the single outlet in the cabin. You can use the outlet in the bathroom to charge iPad, cellphone, etc.