This is a next to perfect house on a beautiful island. I've stayed there for 4 weeks and I felt excellent. It's spacious. It's well furnished, apparently by someone who cares. It's well equipped (someone might miss a dishwasher), everything there for cooking, preparing coffee etc. Even spices are there. And books to read (mostly spanish, but I left an english one there). It has an (electrical) heating in each bedroom (but not in the spacious living room), that is big enough to heat the room. That might be important during the colder months, since the house is located at an altitude of about 400m above sea level. It has a beautiful garden around the house, and Mary Carmen takes care of it a lot. From the house, the terrace and the garden it has beautiful sea views.
However, no house is perfect, and so isn't this one. It has exactly one disadvantage, although I'd consider it to be a small one: It's next to a road. There are cars, not many, maybe 1 or 2 per minute during "rush hour" and 1 per 5 minutes during late evening (while I stayed there). You can hear them, they're not loud, and I wouldn't call the place noisy. The cars didn't bother me, although I'm sensible to car noise, but it might bother others. You should know, and you should also know it wasn't a problem for me who usually is sensible to car noise.
Mary Carmen and her daughter Paula are very friendly and caring hosts. Paula speaks English well, Mary Carmen only remembers she took French classes at school. If there's something to be done, I'm sure they'll come around as soon with you as they've done with me.
In short: If I'll visit La Palma again, I'll rent this wonderful place again.
And if you think this review is too panegyric: Mary Carmen didn't ask for it. I've offered to write it myself, because I felt so good there, and she accepted.