I stayed at Javier's place during a workation in Januar, so about for week. Javier welcomed me in the flat when I arrived, handed over the keys and gave me a short tour of the appartment. He was super helpful when I had questions about the flat and the surroundings and responded very quick on my messages. The flat is quiet, has everything what's needed, and the location is great. You are immediately in the city center and everything, supermarkets, coffee-places and bars are within 5 minutes walk.
Even though I ended up working from a co-working space, the internet connection in the flat is really fast and I could have easily worked from there.
I would highly recommend staying at Javier's place and 10/10 would do it again.