I have used it a couple of times talking to the folks at the gate. Horrendous weather at Larnarca that we were due to fly from on BA. We watched the inbound BA flight hold over Paphos and then land there. We spoke to the gate agents (we were in uniform). They spouted the usual "oh they'll be here soon". To which we showed them FR24 "no they won't. They've just landed at Paphos". "oh". Any way, they were not surprised when the call came through that we all had to bus to Paphos and airline from there.
I use it often when airlining to see if the flight will depart on time.