The apartment is in the equivalent of Oxford St in London- by a very busy main road 'Gran Via' and also nearby to malasana which is the most trendy and bohemian part of Madrid.
I was disappointed by Melvin's hosting skills, as we struggled to get in touch with him when we arrived- which was around 9pm but eventually did (even tried to send messages through airbnb but no response) eventually someone let us in, but when we head out for dinner and checked the front door key- it didn't work. So it took another two calls to melvin to get someone down to the apartment to check the keys again, then we were given a replacement key and then we could leave the apartment. This took a while to sort out and with us having limited Spanish (almost none) and the person who met us having no English, it was a lot of alternative communication but we got there in the end.
The apartment was lovely- very clean and had everything we needed including a hairdryer and an iron.
One problem we had was with the wife- it was slow to non-working most days, which made it difficult to do our research to plan our day- but we went to a nearby coffee house every morning which was gorgeous and had fast free internet.
The bed was also quite hard, but this was bearable for four days. Overall the apt was fine, but I was disappointed with Melvin's hosting skills, as they were non-existent and we had arranged for him to come to the apartment at 11am on our last day to look after our bags before our flight and no one arrived.