I lived in flats in Prague for years, and was happy to find this one was better than expected. Sergej and Tatiana have done a great job remodeling, with a nicely appointed kitchen, and fabulous indirect lighting. The location is great, and only a 2 minute walk to Karlovo namesti metro & tram lines (plus other tram line options in other directions). There are several fantastic restaurants around the corner on Myslikova street (Myslikova restaurant delivers great versions of Czech classics like goulash, schnitzel, and svickova; there is a small indian restaurant around the corner from there that does great curries).
Right now, the building was undergoing renovations/construction, which is why Tatiana double-checked on my expectations. They are building an elevator into the central core, and a lot more. However, it wasn't nearly as bad as I feared, and didn't really bother me. The core stairway is obviously messy, but the flat is clean, well-lit, well-appointed, and comfortable.
I would stay at this flat again without hesitation.