Might I offer the suggestion of looking at the way the doors were placed on QM2? You want at least one wide set of doors for passengers to embark/disembark at port (no need for the system you have near the stern, any ramps will be stored internally). I'd make the ones on the lower of the two decks smaller and the ones on the upper of the two decks larger. I'd also get rid of the shading around them - they are going to be flush and sealed when underway. I also figured out what was bugging me about the forward pods. I'd move them up a few pixels so they are on the large gently slopping part of the hull.
All in all these are minor things, and I'll be stealing this drawing (with full credit) for future use