Use it with 100% response, but some is quite slow. I used it once boarding a flight in DUB to request an early check in at an ORD hotel 8 hours later. They were prepared for me, and it worked out because "you were the one on the app!" And I use it to confirm my room type is available, or when I am arriving, that the shuttle actually works, etc. Basically, it is a good tool to be proactive, but not something I'd rely on for an upgrade or something at most places. But it works.