Arrived at St Petersburg one day early, took a cab to the hotel we booked online, then took a cab to the boat dock the next day. No problems and STP is easy if you are within walking distance of the City Centre, as we were. English widely spoken. If you are using taxis, write (or have somebody write) the address in Russian. Even better, spend part of a week learning Russian Cyrillic before you leave home (it's very easy, although you may not know the Russian word once you translate it). This will save you tons of time when looking for restaurants, etc. Google Maps does NOT show the boat dock address correctly (it shows the address in the middle of an industrial road, under a highway bridge a half mile away from the correct location!).
All of the boat staff were Russian, except for the concierge, who was Bulgarian. Absolutely great service and enthusiasm - five stars for the staff!. The guides were great, the buses pretty new and we took advantage of all the "Do as the Locals do" tours and walking alternatives (instead of busses). Food was always great. Lots of non-meat alternatives. Breakfast & Lunches (and some late dinners after the ballet or other shows) were buffet-style. Wine was like other cruises, just so-so. Older well-traveled crowd, no children. No pool, walking deck, kid-type games; this cruise is for adults who aren't afraid to travel and interact with other cultures. Everything perfectly safe and enjoyable.
This was our ninth cruise (fifth river cruise) and, except for a small-boat cruise down the interior Amazon, probably the best. Fairly basic on-board facilities, especially for a Uniworld cruise. Very small fitness room and library. Massage was just OK. Very nice 24-hour coffee/cookie rooms which we used every morning. Onboard entertainment was simple but very nice; nightly musical concerts from a pianist and/or a saxophone player and/or a balalaika player and/or two singers. Daily lectures about Russian history and culture which were frank, open and extremely well done.
Small quiet cabin and bathroom (very small shower but I'm 6-ft 190 lb and did fine). Nice balcony but the view while docked in St Petersburg and Moscow (6 days of the tour) was to the shore. Beds were very comfortable. Small TV with limited channels. Adequate closets don't really allow your pants to hang freely. A small refrigerator is provided on one side of the closet and a small safe on the other. We brought extra hangers and just left them when we left. Climate control and lighting were fine. Housekeeping was very good. Past Uniworld clients (like us) get free laundry once a week per person. Turnaround was 48 hours. No complaints here.