As Airport-Citycentre facilities go this one is close to third world level. It is incredibly slow. Transfer to and from the TTC is an obstacle course and will likely remain one even after Union Station work is finished. Transfer to and from cabs at Union Station is also cumbersome. Unless you already know your way around Pearson the station is difficult to find  and once you find it picking the right train is another challenge as the signage leaves much to be desired.

The basic problem is that due to a lack of early planning the window for investing the money required to build an adequate facility had been missed. The present jerry rigged solution is modest but expensive due to the "expert" McGuinty/Wynne financial management.

The root cause is that it wasn't built before Toronto's only natural recreational asset, the Islands, was in part sacrificed to DeLuce's obscenity. After that the support of influential parts of the community for an adequate Downtown-Airport link evaporated.