Although we have traveled extensively, we have always done it by land. SPB, Russia has long been on our bucket-list and my brother recommended a cruise (he had done the port of SPB on another cruise line). After a lot of research, we booked NCL.
I must say, after reading many less than favorable reviews of the SUN, we were pleasantly surprised. Love the free-style concept! Never have to dress-up (saves valuable luggage space).
Liked the buffets (food was always edible although often somewhat bland ... but for the price, I am NOT complaining). There was never a wait in either of the main dining rooms. Many options available ala specialty restaurants (we didn't partake).
Ship was very easily to navigate .... room was just dandy (inside cabin, deck 8)...much more spacious than I had anticipated, beds much more comfortable than those to which we were accustomed in 4 star hotels in many european cities. Our cabin steward was super ... kept our room spotless.
Staff very polite and helpful. Used only one shore excursion thru the ship ("Stockholm on your own" - just utilized the transfer to and from Stockholm) and that was only because we tendered in Nynashamn. For SPB & Berlin, we utilizes a private tour company, Alla Tours. Helsinki, Copenhagen, and Tallinn were easily done on our own.
All in all, we had a wonderful time and we would not hesitate using NCL in the future.