I agree with Cruise Fanatic. I've enjoyed all my NCL cruises and I've had one on the Gem and it was great. NCL is different from the other lines mainly in dining, but probably differs in other ways as well.
The Gem itself is beautiful, the staff is very attentive and although food is very subjective, we've always had good to great meals. Look for the sticky buns in the buffet at breakfast time.
Do you have any specific questions?