Holland America Line (HAL) prides itself of being a "signature of excellence". That is far from being true in our experience. If I had to grade them, a "C" would be a fair grade.
Certainly, you will find high quality food and an attractive international atmosphere, but there're aspects where HAL needs clear improvements, especially during Summer cruises. If you're travelling with children, you may want to consider other alternatives such as Royal Caribbean or NCL (Norwegian).
A few examples of why HAL would be a "C" and not an "A+":
Quadruple cabins have a bunk in the ceiling (something that it's not detailed y HALs website).