Picked up the cruise in Palma (most boarded in Barcelona) speedy and efficient and straight from airport to cabin within one hour, no queues and room was ready by 1PM and luggage arrived a couple of hours later. Cabin spotless and well designed as was the ship as a whole
Liked - Main "Grand Pacific" Dining Room, not as spectacular visually as RCCL but food was of a more consistent and higher standard particularly steak/meat dishes. Never had any waiting for a table issues we just timed our visits to avoid peak times and walked straight in every time. Variety and standard of buffet dining also good.
Relaxed "freestyle" atmosphere and mix of guests with many friendly & interesting Americans and fewer Brits which we prefer as you feel as if you are on holiday. I believe P&O is full of Brits so would avoid that type of claustrophobic "Brit exclusive" package feel.