We had an absolutely dreadful experience during and after our Oct 2004 cruise down the Mexican Riviera aboard Holland America's Ryndam.
1. At some point during 7 of the 10 days, none of the toilets on the ship - both those in the cabin and in the public areas - would flush. Typically this would last from 1 to 5 hrs and, as you can imagine, made for some unpleasant odors throughout, AND POTENTIALLY SOME HEALTH ISSUES AS WELL.
2. The service was very inconsistent, and we weren't sure if they were not trained, or just poorly trained. For instance the restaurant staff was far from professional. They would occasionally take orders from the men first, and then even serve the men first, leaving the ladies to sit there and wait.