Experienced river cruisers (we had done three before this one- Danube and Rhine (both on Viking) and the Douro (Uniworld)) will find familiar things to like on the Waterways of the Czars journey, but overall our experience did not hold up well to our five star experiences in Western Europe with Viking and Uniworld.
The big one is that for both Moscow and St Petersburg, the ships tie up about an hour out of city center so if your idea is to enjoy a night time stroll after dinner in Red square or at a Moscow club before returning to the ship, forget about it. Every day in these two cities required many hours on the bus just getting to/from city center attractions. On free days we took the subway which was a cab or shuttle ride from the boat. That of course is part of the adventure. Toughing it out on the bus is one thing; it also means you have significantly less time to spend enjoying attractions (e.g. less time in the Hermitage). The city tour option takes you by the Church of the Savior on Spilled Blood and St Isaac's but not inside. Luckily we went there by subway for our free time one afternoon. They are both amazing, but the Church of the Savior on Spilled Blood is a lifetime don't time. Google it up and see what I mean.
Also be aware that Russia has more than its share of thieves and our luggage was gone over by someone between the plane arriving and its having been brought to our cabin. When we reported our losses to the purser, he lamented that while their security was getting better, this is Russia and it is a big problem. So be forewarned not to carry anything of value in your luggage (good advice for any destination).
Cabins are fine and up to western river cruise standards. The layout of Russian river boats is not as good as those that ply the Danube and Rhine but acceptable for sure. Food is fine, but a tad below the Western Europe offerings. Lectures are excellent as well they might be as they provide a nice respite from the monotonous scenery -- endless stretches of birch trees.
Moscow and St Petersburg are well covered elsewhere and you will enjoy them as we did (once you get there). I recommend that you use the subways on your own; it can be a bit of a challenge but Russians are very helpful and it will help you create good memories.
There isn't a lot to see along the way between the two cities (no castles and charming towns like in Western Europe) as you gently sail between destinations. The destinations though are all fun though a couple exist to please tourists -- Mandrogy and Kizhi come to mind. The former is essentially a manufactured tourist attraction (think Disney Expo) that simulates an old style Russian village. It is principally populated with superior artisans at work on on high style matryoshkas, wood carvings, metal work etc. Cart and Buggy rides are fun. I highly recommend that you spend your best souvenir dollars here. The quality here far exceeds what you'll see at the ubiquitous souvenir stands throughout the rest of your journey.
Kizhi island, a UNESCO heritage site, is a photographer's paradise. They have preserved the most beautiful wooden Churches (think 22 wooden domes on one church) and other structures which date as far back as the 17th century. It is stunning and uncrowded because of its remoteness on Lake Onega.
The other stops in Kirilov-Belzersky, Yaroslavl and Ulglich are also very good.
If your goal is principally to see the world famous offerings of Moscow and St Petersburg, I recommend that you do a land tour and stay in hotels close to the attractions. If you've see the two cities before and the river experience is always a big attraction for you (unpack once, etc.), you'll ertainly enjoy this trip.