My wife are I were down last weekend for Ultrafest and charged successfully. There were 5 other Tesla's there when we left so it appears these will be popular. Charged from about 100 miles rated range in my MS85 to full 90% while we had an early dinner at Tacology (it's really good) and had to pay $6 for parking. Tesla not working out something with the garage for Tesla's to have at least one hour of free parking was a real miss.
The directions in post #79 are dead on. Basically, once you enter from Brickell and get your ticket keep making left turns until you see the chargers.
I was able to remotely check my car's charging progress from the app with no problem whatsoever while we were dining. However, I wasn't in the garage long enough to check signal on my cell phone.