I love EVERYTHING about Rosa's apartment.
The location is perfect. It's is in walking distance (about 5 min) to the main plaza de Sol, also to Plaza Mayor and Prado Museum. Plenty of food around, and just add a few minutes, you arrived at the shopping district if you need to do some retail therapy. Yet, the place is located in a residential street where it doesn't get busy even at night. You can definitely sleep at peace there.
All the description about the amenities in the apartment was accurate. You got everything you need; but of course without a toothbrush :) Still, she provides hair dryer and even hair straightener (very useful for girls I reckon). Kitchen set is clean and complete with all the utensils.
Laundry can be done upon request for free, and we got it done in 2 days (gave her on friday, finished on sunday) since she's busy on saturday (might be faster if she's not busy), which is still TOTALY fine with us. It is helpful enough since we've been travelling for almost 3 weeks.

Room was not huge, but enough for 2 persons. We got 2 medium-large suitcase with us, and managed just fine with spaces inside the room. Might feel a bit cramp if 3 persons staying there, but for 2 it is perfect.

Rosa herself is very kind and welcoming to us. She gave us directions to go to the apartment very clearly, also kindly gave us suggestions for places to go and how to get around Madrid.

I totally recommend this place for you. This is the place where you want to feel at home in Madrid.