Ulisis' apartment is very well located directly at a plaza with lots of tapas. especially in the summer the apartment is great, as it is nice and cool. It is very clean and has everything you need for a great stay in Madrid.
Ulisis was always very helpful and friendly and replied immediately my messages. He provided good instructions for the arrival and arranged everything very well.
The only thing you might have to keep in mind is that you have to walk up to the 4th floor without an escalator.