(tl;dr: It was an amazing airBnB experience.)
The building might look a bit scary but the place itself is super clean, warm, has wifi, comfy beds and an amazing bathroom. It's also very close to a tram stop (~100m) so going in the center is really easy. The whole thing felt super "pro"; the instructions were clear, the place had nothing missing, the decoration and smart furniture layout made the somewhat small place into a really comfy room to go back to after long days of visting the beautiful city of Prague. At that range price I have a hard time believing you could find a better deal, We really had a great time there!