David & Lucía's place is very small, but perfectly adequate for a couple, it has everything one might want or need. We stayed for a week and even though it unfortunately rained quite a bit, we never felt cramped.
The hosts were incredibly helpful, answering questions very quickly and supplying exact and detailed instructions of how to get to their flat and many useful tips on activities (and great places to eat). Location of the flat is also a bonus - we walked everywhere and there are a lot of great places to go out for meals and/or drinks in the evening very (I mean VERY) close by.
I would definitely recommend David & Lucía's place to any couple wanting to explore what Sevilla has to offer both culturally and culinary - I would stay there again if I was to go back.