Here is a rather long review from a first time cruiser. I felt a duty to publish something as I had lurked in this group and mined information in advance of our trip.
Choosing the trip We were new to the world of cruising and went in to it excited, but still a bit unsure about our decision to go. We wanted something special to celebrate our 10th anniversary and we were getting the chance to leave the kids with family for the whole week. We had never been to Mexico and never really had the desire to go, but this is what fit our schedule the best. We had the choice of Carnival or RCL and chose Carnival as we could get more room for the price. We booked a Balcony Guarantee 4 months before the cruise through Costco and were eventually assigned (on embarkation) an 8D on the Empress Deck (#6139). The cabin was starboard side, forward which gave us a view of the sunset from our private balcony most nights.
Embarkation Day (March 7th) -- We live in southern California so we had the benefit of having our family drop us off at the terminal. We arrived around 11:00AM, said goodbye to the folks and the kids and went to early check-in at the Queen Mary. I think we got in on the tail end of this as the sail/sign cards had already been transferred to the main terminal building and the early-check in line was shrinking. We had done the Fun-Pass entry ahead of time, so the check-in seemed rather useless until we saw the (non early) check-in line to get in the terminal. Now we understand.