Maria was a very nice and talkative host.
The location is great! You can walk nearly everywhere!
The room is nice but rather small and when people smoke in the restaurant downstairs the smell enters the room...
The shower is a bit special, but we were able to handle it without further instructions ;-)
And before you use the oven - talk to Maria! In the fridge we had our own space.
The last three days we spent with Gustavo, a good friend of hers. He is very nice and talkative (but only Spanish) as well and a good cook who likes to share his food - so we enjoyed a lot of homemade cake and bread. But he's not very punctual (we are Germans.. :-D ) - for us it still worked out well (and he was flexible with the times!)
And that's probably the 'biggest' problem with Maria's flat: she only has one set of keys. So you need to think and plan at what time you'll be back..
Anyway, I would recommend to stay there!