Hi Smurfette, welcome to Cruise-Chat! My suggestion is to sail without any preconceived ideas about anything. I have sailed 5 times with NCL and enjoyed each one. We just returned from the Epic and she is indeed worth sailing on. She is a beautiful 1.2 billion dollar ship. I've not sailed on the Gem, but have heard good reviews from others. Cabins on any ship are small, so with 4, you're going to be a little cramped in a balcony, 3 would be no problem. And depending on the ages of your children, 4 is probably doable. We were not allowed to see any of the suites or mini-suites on our cruise as they had gates that you needed sail and sign cards for entrance. From the outside, they seemed much larger than our cabin, but that could have been an optical illusion.
I totally agree with Kraftsinc, the sticky buns are great! The key lime pie at dessert is wonderful, too!
I believe NCL has the longest time in Bermuda, so that is a plus, too.
I really don't think you'll be disappointed.