My partner and I have been on four cruises, all previously on Royal Caribbean. We've loved every one of them. But we've long wanted to sail the Norwegian fjords, we realized with five weeks notice that we had the time and NCL had the space ... so we bit the bullet and booked this cruise. Every minute of it, every dollar spent, was worth it.
We spent five days in Hamburg before the cruise, renting an Airbnb and exploring the city (as well as taking day trips to Lubeck and Berlin). Hamburg is very much worth a few days of visiting before or after the cruise. For our one more night in Hamburg (where I am now), we've booked a hotel near the airport for an early flight.
Taxi is certainly the best way to reach the Steinwerder cruise center. From the town center, it cost us 37 euros. (To the airport area afterward, our taxi cost 57 euros.) Embarkation and disembarkation were very smooth. Long lines (especially since we had no status on NCL), but handled efficiently. All very friendly and pleasant.
We had inside stateroom 8113, a "family" inside stateroom, apparently so called because it has a third pull-down bed if needed. We found it slightly smaller than the inside cabins we have experienced on Royal, but the space was sufficient and well appointed. Three adults would have been unbearably crowded. We really liked that the shower was large enough to move around a bit, although the toilet was oddly positioned to require sitting at a bit of an angle to keep one's knees from hitting the wall.