Our stay at Mimi's was brilliant. The location was great, walking distance to San Telmo and a stones throw from a metro station. The flat itself was lovely and spacious, and came with an efficient heater (useful as it was winter when we went). Mimi and her husband were fantastic hosts and answered all our queries quickly.
The only downside was that there was a powercut twice whilst we were there. Mimi and her husband worked hard to get that fixed promptly and it wasn't something that could be helped.
Overall I would thoroughly recommend this apartment!