Manuel was an excellent host: ensured we had everything we needed and went out of his way to provide extras. Communication with him was excellent: he responded within minutes of sending a message. And was always able to answer questions and offer advice.
The photos really don't do the apartment justice: the terrace is stunning and the apartment itself is beautiful. Although the apartment is compact, it has everything you need. Having said that, we were incredibly lucky with the weather and didn't spend much time in the apartment itself.
As others have mentioned, the service lift you use to access the apartment is, well, interesting! We didn't have any issues with it - in fact it was fun! But, I can imagine that it might not be for everyone.
The location was great for us: we didn't want to be surrounded by tourists on La Rambla. Within 5 minutes walk of the apartment there's a bus to Park Guell, a bus to Barceloneta for the beach, and Muntaner station (takes 11 mins to Placa Catalunya). There are numerous shops and supermarkets within 2 mins walk of the apartment and a couple of nice bars and restaurants.
Overall, I can't recommend Manuel's beautiful apartment enough. We'll definitely be back!