Owner/Host:
Angel is a great host and he made us feel welcomed from the second we came into the door. Instructions and rules of the house were pretty reasonable and clear. Concerns were handled in a great friendly manner.
Perfectly happy with the owner.

Location:
This studio apartment is located in an amazing "Gracia" neighborhood with huge number of places to visit nearby. That includes shopping (all kinds: from construction tools to high fashion boutiques), tapas places and restaurants.

This location could not be any better. In our 7 days stay in Barcelona we did not have to use public transportation once. We were able to visit most of the "must see" sites by simply walking to them.
Sagrada Familia, Mercat de la Boqueria, Park Guell, Arc de Triomf and other places are all close enough to just walk to. Not even going to start describing all the food options available nearby, because the best thing is just to wonder around the neighborhood and discover all of that for yourself. It's totally worth it.

I probably have to mention that my wife and I enjoy walking quite a lot, so if you normally take a bus to visit grocery store 2 stops down the street then, maybe, you should resort to the same way of traveling in Barcelona. Public transportation is supposedly very good, but again, we didn't have to use it.

TL:DR Amazing location to explore Barcelona

Place:

It's a studio type of place with bedroom/entertainment area combined. Kitchen / dining room is actually a glass-walled section of the patio. Wall panels can be opened in the daytime and closed for colder parts of the day. Overall, this provides great authentic experience of Barcelona style dwelling. Place is well equipped and has everything a traveler might need.

A couple of things to note:
This place is not really suitable for any sort of serious or even semi-serious cooking. There is no hot water in the kitchen, so doing any dishes besides rinsing glasses is not going to be fun.
This place is an "attic" (read: located above the top floor)and there is no elevator, so multiple in and out missions could be challenging (but healthy too!).

Overall:
Great place to stay in for Barcelona exploration. Highly recommended!