Has anyone used passenger assist on trains?

If so, does it actually help and have they turned up on time and everything?

Put in a request as I'm heading to stansted airport on Thursday and there's a transfer in london euston station and I'm not sure ill cope well in that station (been once before but I was with people and im travelling alone this time), but worried they wont be useful or wont turn up on time and I obviously need to get to my airport as I have a flight to catch - I'm meeting my friend at the airport so flight wont be an issue