I booked this cruise because of the itinerary (Christmas AND New Years on the ship).
There were no issues with embarkation and disembarkation. Both were fast and convenient.
The Gem is a beautiful ship with a lot of things going on during sea days and in the evenings. Because of the Christmas holidays, there were a lot of kids and teenagers on board.
The cabin had a porthole window, which was bigger than I had expected. I had an unobstructed view and got natural light into the cabin. I think the cabin is big enough for 2 people, and there is a lot of storage.
I found the cabin a bit noisy though - I heard various ship noises but also the neighbours. I could hear them talking and it frequently sounded as if their kid was jumping off the beds - I heard loud thumps. The other drawback is that, on land days, the gangway is on Deck 4, so there is a lot of traffic of people getting on and off the ship.