I'd read quite a few reviews and some negative comments, but I have to say that the Ruby Princess gets top marks in almost every category.
Check-In was very smooth.
We were booked on Traditional dining but because a number of our shore excursions ran into making us late for the early sitting, we were still welcomed at our table in DaVinci's when we could get there. The food was excellent and the staff went out of their way to make sure we were pleased. We had some senior ladies at our table and the waiter or assistant waiter even cut up the meat for one.
Our stateroom was right at the entrance to the elevator lobby and it was still quiet. Lots of closet space (for two women). Air conditioner worked wonderfully well. Shower has curtain closing and is small. We wondered how some very large people could cope in them.