My wife and I spend Aug 1-8, 2009 on Carnival Liberty in the eastern caribbean with 2 other couples. This was our second Carnival Cruise, our third on "floating hotels" and our tenth if you include smaller boats such as Windjammer, Starclipper, and crewed and bareboat rentals in the BVI.
We drove down from SE Georgia in a rental car and dropped it off at the Hertz HLE Downtown office and they shuttled us over to the Port of Miami - about a 5 minute ride. This was very convenient and was cheaper than paying $140 parking for the week. Embarking was very fast and we were on the boat within an hour of arriving at the terminal. Our cabin was available as advertised at 1:30PM and our luggage arrived by 3:00PM. We had a balcony cabin on the Upper Deck (deck 6). It appeared that the cruise was completely sold out. There apparently were over 900 kids on board. We knew there would be a lot of kids but it wasn't an issue.
The boat was very clean and the crew appeared to work very hard to keep it that way. The main pool area was a zoo. We mostly hung out by the adults only pool (which often had kids in it - sigh) and the area above the adult-only pool.