Brian has places in more than one building, so I can only comment on the place I stayed: "★Prime Central Classic ★Lovely Modern Renovated." But I can say that it worked great for me. Location was the key. I wanted to be close to specific sites, while also not being too close to a lot of late night noise. This place was PERFECT for that. At night, it is one of the quietest streets in all of downtown. And this really is in the heart of Santiago Centro, so the feel of the place is really surprising. There really are just very few comparable locations.
And Brian and Erica were great. Very responsive when I had issues. Lightning fast, in fact. The apartment is quite small, but is in great shape and quite clean. That's important because Santiago is quite dusty and gritty, so if a place isn't kept clean it shows really fast.
I was only really using the apartment to sleep, so it worked fine for my needs. The kitchen seemed small, but perfectly adequate. Personally, I didn't use it much since there are many good quality, cheap places to eat in the area. But I think it would work fine if you are committed to preparing your own meals.
Overall, I felt quite comfortable. And since I stayed there just over two weeks, that was important.
One tip if you are there in summer: since the windows face west, remember to close the curtains before you head out for the day. Otherwise the afternoon sun will heat up the place.