The location is good, right in the heart of Malasaña, close to restaurants and bars and you can walk everywhere.
The downside is that the only windows in the apartment opens to the corridor where neighbours will walk by so there are not much privacy if you open them. But it could be a but stuffy and quite dark indoor if you do not open some windows.
And there is a pest problem in the bathroom, as I keep seeing silverfish insects crawling out from a hole under the shower stall. It's a bit annoying to have them all over the bathroom floor all the time.
Otherwise it's not a bad place to stay in Madrid.