This place is a total gem.
It's so central (5 minutes at most from the Alcazar/Cathedral/River). It has all you could want and in addition to that a delightful private roof terrace which catches the sun all day.. It was great to eat breakfast on and would be ideal for 'cocktail hour' before you go exploring Seville again in the evening.
Seville city centre is small but this location meant you could easily pop back to the flat if you got tired or the heat was too much before heading out again (it was 27 degrees in February, so I can only imagine what it would be like in summer).
The flat was clean and cool with a really big bedroom and a cosy kitchen/dining area on the top floor.The air conditioning worked amazingly (again, i'm sure this would be important for summer).
It's in quite a popular area just off a street with bars and cafes which is great but, if you're a light sleeper you might find it a bit noisy after 11pm. Only other thing I'd mention is it's up 2 flights of quite narrow stairs (with no lift) so I think if you had lots of heavy luggage it would be a bit annoying getting it up and down the stairs.
Check in was really easy with hosts being very communicative and helpful on arrival. It's also a really straightforward 5 minute walk from the stop for the airport shuttle bus which meant I didn't have to worry about taxis or anything from the airport (stop is Paseo Colon/Torre del Oro).
I would certainly stay here again and would recommend it to anyone I know who was thinking about staying in Seville.