Just returned from an 11 night Ancient Mystery tour on MS Noordam (2nd time on board the same ship). Fabulous itinerary made even better by the changes, due to recent disruptions in Egypt, from Port Said & Alexandria to Ashdod & Haifa in Israel ' even more of a bonus that HAL gave us $100 pp. as compensation.
Primarily we always chose a cruise based on itinerary / ports of call & Holland America Line excel in this area. The fact you can chose your length of stay i.e. 11 days, 22 days or even 33 days (for the lucky few), is also good as is the fact that the cruises don't loop ' you start in one port & end in another so can get further (although aware for some that embarking & disembarking in differing ports may be an issue). Secondly it comes down to cruise line ' chose a line as you would when choosing a resort & hotel ' they all differ greatly, even within a line it can depend on the individual ship, time of year travelling & even itinerary. Most cruise lines will be busy in school holiday & have kids on board ' some more than others. There are pros & cons with every cruise line.
The MS Noordam is understated but elegant. She isn't the newest ship out there nowadays - 2006 - which is far from old but in ship terms she is showing some small signs of 'wear & tear'. However she is kept it pristine condition (unlike Thomson ships) & constantly cleaned.
Cabin v quite - no complaints