I have been on the Pride of America 5 times-- in 2006, 2009, 2011, 2012, and this past cruise in 2013. I have sailed with NCL a total of 17 times.
In my mind, the NCL international fleet has been 4.5+ star in my mind, although I have not been aboard the newest 140,000+ GT Epic and Breakaway yet. In 2006, I considered the NCL America ship Pride of Americas as 2-star. It slowly improved to 3.5 star by 2012 and today nears 4-star on a good day.
But there are a lot cutbacks and "missing" amenities that experienced cruisers would notice. My guess is because of the high expenses this ship incurs. The Pride of America is the only U.S. certificated cruise ship of its size or larger...in fact, you would go down many, many gross tons to find the next U.S. passenger ship.