The location is the best, just 2 blocks from Sagrada Familia. There are many good restaurants and supermarkets around. The neighbourhood also looks safe.
The host would reply to our questions or requests soon. There are detailed instructions to help us check-in and get into the room.
The front door and the street door are controlled by internet. The upside is that you don't need to meet the host or carry the key around. However, if you do not have connection to internet, you would be unable to open the doors. In addition, there is no way to lock the door from inside of the flat. Luckily I brought a lock and used it to prevent any one from breaking in.
One problem with this flat is that there is no manual for the electrial appliances. Since there was no chance to meet the host, when the boiler didn't worked, we would have to do the troubleshooting ourselves as the host could not immediately deal with the problem though he had given some advice as fast as he could.