I only went to Hamilton (West Harbour), last train to make it there on time, then first train back (3:25pm, though it waited a couple of minutes to let more on). It was crowded, but didn't initially look quite as bad as the photos above, though it got worse as more boarded on each trip. On the way back toward Union Station, lots of people in Leafs and Blue Jays gear were also trying to board.
Edit: Looking at the photos in the second post below, I'm happy I left right away and didn't wait another hour for the next one. And it also sounds like it was better than driving from the stories I've heard.