I have used Bitcoin ATM once because of curiosity, the time of transaction was fast and it is very user friendly, you can also see some instructions on how to use it but I'm not planning to use it ever again because it charges big amount of percentage of Bitcoin you transacted. It also hard to locate Bitcoin ATMs here in my location and if you found one sometimes it's not functioning. I won't waste my time finding and using Bitcoin ATMs again since there are lots of options here to buy and sell Bitcoins with lower transaction charges.