Greg's place is located close to the metro and makes it easily accessible to the entire city.
The apartment is nice and clean and the room we stayed in was very comfortable. It's a great budget stay and worth it for the low cost.
However we did not realize he was renting out both rooms, and he himself was sleeping on the couch. 5 people sharing the bathroom and being contained to just your own room was a bit tight on space.
Our first night with just our room occupied was much more comfortable (may want to ask in advance if both rooms are being used)
Overall Greg was very nice and helpful and we would recommend this spot if you're trying to see Barcelona on the cheap!