I've only used the ferry once, it was very nice apart from the force 10 gale in the Bay of Biscay on the way home, you then realise it's still only a ro ro ferry. Its got bars, casino, cinema, swimming pool and entertainment, but it is expensive.
Anyway that aside, a little story.
When I was staying at a site in Northern France a couple of weeks ago a tent camper appeared on the pitch next to me. We got chatting and he told me he should have been on the Pride of Bilbao but they had cancelled his crossing and offered no alternative (not that they could I suppose). Apparently one of the props on the ferry had collected a fishing net from somewhere and had to be taken out of service for a couple of days to get it sorted. Unfortunate but these things sometimes happen.
P&O contacted him, cancelled his crossing and said there was nothing they could do. They did give him a full refund. He then had to engage in lengthy discussions for compensation. Eventually he was offered a small amount of money and a one way crossing Dover/Calais, he had to pay for the return. I thought this was terrible. He had to book standard crossing rate for his car and trailer and ended up paying twice as much for crossing one way with P&O compared to my return crossing price with Norfolk Line.
The moral of the story is this. Unfortunate incidents happen that cause ferrys to be cancelled. If a Dover/Calais ferry gets cancelled you catch the next one an hour or so later or they make arrangements for you to use another company. If the one and only ferry on a long sea crossing gets cancelled you're stuffed.
I've towed to Spain a number of times. I'd rather use the extra money and time taken on the crossing to drive.
Different people have different opinions and the crossing is enjoyable but I go to Europe for my two/three weeks at various sites on land, not for my 24/36 hrs on a ferry.