I had a fantastic experience with Stay U-Nique. Communication was excellent. I was able to arrange to bring my bags to the apartment earlier than the usual check-in time. The apartment was very clean. The kitchen was well-appointed with everything you would need to cook.
The location was excellent, near La Ramblas, and easy walking to many sites. There is an outdoor cafe near the apartment that always has people eating there. I ate there with friends and was very satisfied. There is a small grocery store nearby. The metro is very close as well as many bus routes.
I definitely would highly recommend Stay U-Nique and this specific apartment to my friends and colleagues who visit Barcelona.