Mariner of the Seas receives high marks for its friendly and hardworking staff, enjoyable entertainment, and a variety of activities, especially for families. Many guests loved the private island CocoCay and found the ship's amenities and excursions enjoyable. However, there are recurring criticisms about the ship's aging condition, crowded public spaces, inconsistent food quality, and extra charges for certain activities and services. While most guests had a great time, some experienced issues with cabin cleanliness, food allergies, and value for money. Overall, the cruise is recommended for its fun atmosphere and excellent service, but some areas could use improvement.