We recently took a cruise on the Norwegian Escape Haven during Spring Break. Thank goodness we were in the Haven, because the rest of the ship was jammed packed...it was like a mix of vegas and cancun on the ship. If this were my first cruise, I wouldn't have taken another. The Haven was great and you basically got to skip every line. Here is my comparison to the The Celebrity Retreat that I took on the Edge. I will point out the Escape was an older ship and the Edge is newer so that might be different in newer NCL ships.
Haven pros:
amazing staff