I attended the lecture as well, and was seated pretty much smack in the middle of the theatre. Mark was quite engaging and I brought some friends along who weren't originally from Toronto (they got lost at some points when he started talking about streets, but overall they enjoyed it).
The feeling I got after the lecture was that Toronto has probably fared alright. Yes, we lost some treasured buildings in the past, but on the other hand, some truly destructive and un-urban projects were never built. Also what hit me is the enormous effect the Depression had on the built form of our city.
During the question period when that older gentleman started talking about watching the pigeons move according to the shadows at Nathan Philips Square I couldn't help but laugh.