I had a very pleasant stay at Sanaz's apartment. It's well equipped, bright, conveniently located, and comfortable.
As others have mentioned, there are a lot of stairs and no elevator, and the stairs are also extremely narrow. If like me you read others mention this in the reviews and ignored it, don't. It's way more than you'd think and a huge obstacle if you have luggage.
If you want to use the couch bed there is an additional fee if you're travelling with just 2 people. This is mentioned in the house rules, but not on the listing itself, and this wasn't clear to me before I booked. I wish I had known this before booking so I'm mentioning it here, but in the defence of the hosts it is clearly outlined in their house rules. Definitely read these before booking, there's a lot!
You don't have control over the heating, although the hosts were very responsive and kind in increasing the heat when asked to. I found the apartment very cold over all though, especially in the bedroom.