Maria's place is the best Value For Money deal you can find in Malaga. I challenge you to find a better location at this price. Extremely central, in the very heart of the city, yet never too noisy for you to sleep.
Maria herself came across as a wonderful human being in my limited interactions with her, and her son Viktor is cute as a button, and speaks lovely English. I wish I could have spent more time with them, but we were always running, so unfortunately, couldn't do that.
The only negatives I can think of are the size of the room (very small), the quality of the bed (it's small and the springs creak noisily when you move), and the cluttered (though always clean) bathroom.
But of you are in Malaga for being in the thick of things, it doesn't get thicker than this, so just go for it!