We just returned from 10 days cruising Alaska and BC and had an amazing time! The Norwegian Sun is by far the most affordable option so it was possible for our family of 4 to enjoy a private balcony and view humpbacks, glaciers, a volcano and sunsets directly from our room.
Having said that, for this low price you get a very basic ship. The Norwegian Sun does have some strengths, but with no movie screen on deck, no variation with the dining (no chocolate buffet, no lobster in the main dining room, etc.), drab decor and laughable entertainment, the ship became pretty boring pretty quickly.
While not offensively bad, everything about the ship was a little sub par. In particular the dining felt pretty institutional. On the buffet, you'll find some foods you really like and some that are awful, but overall it's just so-so. The main dining room was really hit-and-miss. A salmon burger at lunch was tasted fishy and old, while the salmon filet at dinner was quite nice. It terms of the specialty restaurants, we went to Le Bistro (very good) and La Cuccina (a bit disappointing).
Spacious and very functional. Mattress was a bit uncomfortable.
Bathroom was small and functional. I didn't find the shower that small or difficult and I'm 6' 2" tall.