This hotel is really clean, quiet, and simple! The rooms are remarkably cozy and fresh, the beds comfortable and warm, and the bathroom spotless and well-stocked with towels and sublime toilet paper (not sandpaper like you get in some expensive hotels!). To top it all off, the staff was incredible. Front desk personnel were very helpful and friendly, even providing laundering services! Room service personnel were quick, thorough, and thoughtful, changing sheets daily, cleaning the bathroom impeccably, and ensuring all amenities, like tea bags, were restocked.
Just outside the front door are restaurants, coffee shops, and high-quality grocers. Only a couple blocks away is a subway station which lets you zip around Saint Petersburg easily.
There's only one thing I think could use improvement: WiFi. As an international visitor, I relied heavily on WiFi wherever I went. WiFi at this location was intermittent and splotchy.
On a more personal level, this was my third visit to Saint Petersburg. I wanted to stay away from the touristy areas and be in a place where I could see regular Russian life. This hotel is right across from a university, in the middle of many dwellings, and quite a ways from Nevsky Prospekt. You see daily life here.
Overall, I loved my stay at Rotas on Krasnoarmeyskaya. It isn't opulent, but it was excellent.