I have had problems with T1New signage particularly when it comes to finding the "public transit" bus bays. At one time the TTC ran on one of the upper levels, but has now been moved to the so-called Ground Level along with the AIRPORT EXPRESS, GO and MISSISSAGUA transits. But as noted, there are no clear signs directing people to anything more than Parking and Taxis/Limos as are there few if any escalators that go down to the Ground Level from the Arrivals Level. One must find the only set of elevators that do so on the wall separating landside from airside, and even these provide no detail of what services are offered from the Ground Level. The ones in the central landside hall just go to Parking and Departures Levels.
I have pointed this out to "officials" on several occasions, but nothing has yet been done. Guess they're waiting for the 18% landing fee increase to go through next year so they have the spare cash!