Of all the concourses in the city, the one under Union Station is the poorest designed, considering the complex uses that it accommodates. If ever wayfinding fails passengers it is there - garish and competing signage systems, poor orientation to the building as a whole, and failure to make the travel sequence the passenger must negotiate - from buying tickets to reaching the platforms - as logical as possible through the location of services and access routes. It's a hell unto itself, with no design link to Lyle's Great Hall above either, when what's needed is simplicity and clarity.
The new basement pedestrian retail level will obviously be less complicated functionally, but let's hope it relates to what's above - the GO and VIA concourses, the Great Hall - in its design as effectively as the best of our underground concourses ( still the TD Centre, I believe ... ) does in reminding us of where we are and feeling a part of the whole.