Union Station has changed so much in recent years, I can hardly recognize it with all the new construction. I mainly use the GO Station to catch a Lakeshore East train or to grab the TTC. Right now, with all the construction, it can be a bit confusing finding your way around, but I'm loving the improvements I'm seeing so far.
There's also a few retail and food shops open right now (McDonald's -McCafe, Starbucks, Tim Hortons, Booster Juice, Peace Collective, Pilot Coffee Roasters, but you can see there's lots more planned for 2018.
There's also complimentary WiFi and charging stations sponsored by TD Bank which is helpful when you're waiting for your train or Bus.
The staff are also friendly and helpful!