The 25F was awesome. At the time it was introduced, I was studying at the University of Waterloo, and had family in Vaughan. It was a total game changer, cutting a solid half hour off of the next fastest option which was the 25C Express to Square One, then transferring to 45, 46 or 47 to 407. Westbound trips ran non-stop starting from Hurontario/407 Park & Ride, which meant that they could just drive to conditions and usually arrive in Waterloo early, sometimes covering the trip in barely over an hour. I would usually plan on catching bus connections at Laurier which were scheduled to depart as much as 10 minutes
before the GO bus was scheduled to arrive.
It's also noteworthy that they had significantly underestimated the demand for a much-faster service along a pre-existing route. The "F" buses were all completely jam packed from day one, consistently leaving people behind. They doubled the service frequency in the next schedule change, after which the buses were consistently full but not overcrowded. I think it supports my theory that GO's service planning underestimates the effect of scheduled speed on ridership demand among students. They seem to assume that if a service exists, that students will take it because they are "captive riders". See for example how in 2021 they increased service to 2 buses per hour on the 25 Local, without reinstating any express services at all. It's not a matter of operating costs - it have would cost exactly the same to run
1 bus per hour local to Square One + 1 bus per hour to Kipling via Square One.
