Just got back from the cheapest P&O cruise ive ever been on.
Cheap drinks, good service. MDR was supposedly good but for around 20 USD per person we ate speciality every night. Food was very good and service was excellent mostly.
Only problem was the price was so cheap it allowed a much different demographic on board but they weren't a problem. Upside was that the cost was so low that anything less than perfect really wasnt an issue.
Then there is royal which royally rips you off and then has the cheek to not even get the basics right and then expect you pay their staffs wages in 18% tips for zero service.