Konstantin is very responsive and will respond to your question within minutes! We arrived around 1030pm and took a taxi to his place (although he told us about the metro too but we wanted to avoid that at night time). He was waiting for us which was a nice welcome! We messaged him during our stay and he was always responsive and helpful.
Location - pack some earplugs! It's close to everything (10mins) but the street is VERY VERY noisy!!! Make sure you know where the water heater switch is as well! That was one of the first things he showed us and it came in handy!
The unit - please confirm with Konstantin which unit you are getting. I think he has a few units, and the one we got was not the one pictured in this ad. We didn't have a kitchen with stove; we had a kitchen with sink and a hot plate in cupboard. We couldn't fit four ppl if we wanted to as there was only one bed. We also didn't have a fireplace. This unit was definitely different than the one described and pictured in the ad however, it was just me and my husband for 2 days so we didn't care. The place was still nice and met our needs. BUT if you need to sleep 4 ppl and are relying on cooking, you need to clarify with Konstantin that this is what you will get.