When selecting a cruise we look to the itinerary more than what a ship has to offer. We always have a balcony for catching up on reading and rarely participate in group activities or main dining room dining. The Mariner is a good ship and well-maintained. The staff was helpful and pleasant. The food in the Windjammer cafe is plentiful and there were varied choices for every meal. What could be bad about eating french fries morning, noon and night?! My only criticism of the Windjammer cafe is that RCL piped in loud, ear splitting music over the PA system to the point where I literally had to shout to my son across the table from me! I'd much rather hear the ocean rushing by.
The ship is listed as non-smoking but smoking is allowed on balconies. I wish cruising companies would be brave enough to eliminate smoking on balconies! I sat down on my balcony one sea day all set to read and relax only to smell the cigar exhaust of my neighbor a few cabins down! Yuck!
The adult-only hot tubs and pool on Deck 11 were great to have as long as someone didn't bring their baby or under 16-year-old into the hot tub. Despite having "Adults Only" signs posted quite a few guests seemed to ignore the rules. Not sure what RCL could do about that.
Great balcony, wrong side of ship for most ports (it's on the port side), same floor as library, center of ship but close enough to stairs, closer to promenade on 5th deck and a hike to Deck 11 for Windjammer cafe (we try not to use the elevator if possible to work off all that food!), used to staying on a higher deck or in the back but neither was available at time of booking.