My wife and I sailed on the Mariner October 24-31 on the western Caribbean route. It was our first time in a balcony room because for the money we can typically almost cover the entire cost of another cruise by choosing an inside cabin. However, we splurged and while it was nice, we'll cruise two times next time and forgo the balcony.
Overall, the ship is truly amazing. We've cruised 6 other times before including a 17 day transatlantic. We've done all the lines except NCL and Princess. While we don't consider ourselves cruise snobs or even seasoned veterans, we won't go on a Voyager class ship again.
This was our first RCL cruise so I won't put it to the line, but rather the ship. Perhaps it's because its just so big and there's only so much you can do for 3000+ people, but this was nowhere near the level of a Millennium class Celebrity or even HAL cruise.