Our family (myself, husband, 14 yr old son) travelled on the Oceana in July 2007, sailing from Southampton and touring the Western Mediterranean.
A mixed experience. Many parts excellent, others perhaps in need of addressing by P&O.
Getting onboard was hassle-free with a friendly check-in assistant and people to park the car for us (at extra cost). We had booked two cabins - an outside balcony and an outside twin. Ours (with the balcony) was very much smaller because the balcony takes up part of the cabin room. Very clean, very comfortable, but fairly basic. The TV was fairly old, the decor good but more 'Travelodge/motel" than high quality hotel. I understand they are refitting the ship soon, though.