I recently checked out some YouTube reviews of the SV Strizh, and Varlamov's is definitely one of the best. If you're interested in seeing the actual cabin experience, I'd recommend checking out the review on YouTube, but keep in mind it's a few years old, and things have changed since then.
One thing that caught my eye right off the bat is that the hygiene kit looks cheaper now than it did in the YouTube review. Instead of bottles in the shower, the shower gel and shampoo are now in sachets.
On the photo, you can see the shoe horn, comb, brush, and paste, shower gel and shampoo, and a compressed sponge for the shoes.
Tap shoes for sitting in the 'cabin' are pretty basic - they're the cheapest ones, and they're blue. The white ones are a bit rubbery, and I'm guessing they're for the shower.
Some of the issues that bloggers pointed out have been fixed, too. For instance, you don't need to call the steward to lower the upper shelf - the keys for lowering the shelves are already in the locks, and you can do it yourself.
On the photo, you can see the button for turning the light on and off, the socket (there are two of them - one here, and one in the opposite corner of the cabin), radio adjustment (the speaker is turned off by default). To the left, you can see the wallet holder and the wallet itself (don't forget to take this when you leave the cabin - the door will close). You can also adjust the temperature yourself - the regulator is above the window.
There's a safe, but it was locked when we were there.
Another thing I noticed that's improved since the YouTube reviews - there are paper cups near the cooler, not plastic ones. It's more convenient if you want to make yourself a cup of tea.
The water dispenser is located in a common area. The cooler has two faucets: hot water and cold water. I wasn't a fan of the water - it had a slightly metallic taste. But, I guess that's just what you get on trains.
Breakfast!
Breakfast on the Moscow-St. Petersburg route starts at 8.00 and goes until 12.15, just 30 minutes before arrival. You can pre-order a special breakfast 72 hours before departure or when buying your ticket. If you don't pre-order or buy your ticket less than 72 hours in advance, you'll get to choose from three options, plus a vegetarian option. I went for the veggie option.
I really enjoyed my breakfast. Plus, with every meal, they bring out a 0.25L bottle of standard drinking water from Akvania (totally standard for Russian Railways) and a 0.2L Rich juice in a glass bottle - you can choose from apple, orange, or tomato.
I also had a chance to take a shower in my compartment car and it was quite comfortable. Despite being in carriage 17 (which is the second from the end of the train), the shower didn't shake and I could easily rinse off. A large towel is provided, and the curtain works well.
Price.
The full compartment car with a shower for two of us even turned out to be slightly cheaper than if we had taken two seats in a coupe of the same 'Strizh'. Maybe there was some unannounced promotion on the RZD website; maybe tickets for a compartment car are cheaper if you buy them close to the departure time and lose the option to choose breakfast - I'm not sure. But the math looked like this: You buy one ticket and you're buying the entire two-seat 'cabin'; you buy two tickets and you're buying the cabin, but for 1000 roubles more than the price of a full cabin for one person.
I don't know why this worked on the day I bought the ticket, but I recommend not being shy and playing around with the booking on the RZD website if you have time. Until you enter your bank card details, the ticket isn't bought, so go ahead, compare, look at the final price, and choose.
I'm super happy with my experience in the compartment car. The price was amazing - we managed to get it cheaper than the Sapsan and cheaper than a coupe in a simple overnight train from Moscow to St. Petersburg. Plus, we had a shower, slippers, and a pretty rich breakfast. And guaranteed no neighbor in the coupe. The compartment is small in size, but it's completely comfortable. The wagon is quiet because there are few coupe compartments per wagon. Plus, it turned out to be very lucky that we took one of the last wagons: no one walks past us and we don't get any food smells from the kitchen. The kitchen is in wagon 8 or 9. And in wagons 10-12, there's a bit of a smell.
I highly approve of and recommend the 'Strizh' train in a compartment car with a shower and breakfast. And do keep an eye on the prices. It might turn out to be cheaper than all your other options for a trip for two.