Absolutely useless
We prebooked a taxi using this app for the next day - early in the morning (4.30am)to get to the Stanstead Express. The booking was confirmed and even got the name of the driver who would be picking us up the next day. The morning arrives and suddenly at 4am get a message that the designated driver would not be coming - offered an option of finding another taxi and one was found - would be there in 20 minutes. Ok that would still be right on 4.30am. At 4.25 we are told that that driver was no longer available did I want to search for another. We had no time to waste and just rushed out the door and 10 minutes later hailed a taxi in the street. The app was worse than useless. If you book a taxi for a specific time then you expect it to arrive at the agreed time. The fact that drivers can cancel at a whim and the app then searches with no guarantee of success makes this an utterly bogus system.