Malasana seems a safe, friendly area, full of life, bars, shops, cafes and restaurants. These are in nearby streets, so you'll also sleep well.
The flat has everything (including Netflix, DVD, washer/dryer, new kitchen) and the sofa-bed is in its own room. There are also plenty of books & dvds to browse. We really appreciated the 2 balconies and air-con. Temple of Nebod and royal palace are close too.
There is a school next door and an expensive comic-art gallery opposite, with a metro line 3-4 minutes walk away. Lidl and other stores are 5-10 mins walk away.
Would happily go back tomorrow :)