I recently returned from a 12-day Mediterranean cruise out of Barcelona on Royal Caribbean's Brilliance of the Seas. The following are some observations and tips that may be of interest to others.
Overall, I enjoyed the cruise, the ship and the staff. I have been on higher end cruises before and knew not to expect the same level of service and amenities. With reasonable expectations in mind, I was not disappointed. One area of particular dislike was the cost of shuttles from the ship into town. See below for more information.
Barcelona: Boarding the ship for the first time, and disembarking at the end of the cruise was easier than any ship I had been on. This was a very quick process both ways. Although I did not use a taxi, others told me that the costs were reasonable. I used the port shuttle bus, which was 2 Euros and dropped passengers at the Colon Monument. This is a short walk to Ramblas, and about a 20 minute walk to Catalunya. For a nice pre or post cruise hotel, consider the Hotel Gaudi on Carrer Nou de la Rambla, 12, right off the Ramblas and convenient to the Metro. There are rooms on the upper floors which overlook the beautiful roof of Gaudi's Palau Guell (currently closed for renovations). It is very easy to get to and from Barcelona's airport to Catalunya via the Aerobus (different buses to different terminals).