We sailed Mariner last year, and at that time, entertainment aboard was very good to excellent. Be sure to catch the ice show. It's a little bit of trouble to get the tickets, but well worth the effort. Big shows were very very good too, (although this ship had at that time the only two overweight female dancers I've ever seen aboard ship). Still, the shows were not to be missed. Piano bar and all the other offerings were very good. Even the karaoke was good. They had a "Mariner Idol" show or something like that toward the end of the cruise, and that too was lots of fun. Bottom line,,,,you won't be disappointed.
Entertainment on Mariner is OK. Ice show is the best by far. Big problem with entertainment is everything closes by 1 a.m. even the casino most nights. If your looking for late night entertainment in a bar/ lounge you are out of luck they all close at 1 a.m. Preferred entertainment on Carnival Celebration, since retired, best I've had on my three cruises, and on Grand Princess. Grand not as good as Carnival, but far superior to Mariner.
Make everything in life fun. You make the experience fun not those around you.
Beyond the performances, shows all the amusements trademark style night. In Wig & Hammer pub, singing a mournful guitarist-vocalist of sweet melodies and rock classics. Bolero featuring Latin dance music. Schooner Bar pianist played pop songs and torch. All day and night, there is often a kind of performance along the promenade, such as "Enchanted Knights Parade, concerts Krooze Komics, instrumental trios or mini-comedy shows. Mariner of the Seas offers a wide range of excursions in each of the three Mexican ports by Cabo San Lucas and Puerto Vallarta has almost twice as many options as Mazatlan. Excursions range from any form of active pursuit imaginable (hiking, kayaking, snorkeling, golf, scuba diving, zip, sport fishing, off-road jeep, horseback riding) for sightseeing, beaches, meeting dolphins, and Mexican cooking classes cruising yacht