Just got back from the Mariner on the Royal Carribean. It was fantastic. The only gripe I have from the 7 night cruise is that the bathroom light switch for the bathroom was on the outside wall behind the door. So if you opened the door and the light was not on, you had to step out, shut the door and then turn on the light.
We loved the cruise line and this boat - as you can probably tell from how picky this gripe is. We couldn't find anything important to gripe about.