Absolutely fantastic. I rolled into Toronto for a conference and needed to grab a bite to eat between meetings. When I saw the veggie burger on the menu, I knew I had to go.
Coming from a vegetarian-friendly city (Seattle), I've had my fair share of black bean burgers. This. One. Was. Awesome. And it paired perfectly with the fries! I highly recommend... and may just go again in the short time I'm here.
A tip to make walking through The Bottom Line less awkward: enter the main entrance on 22 Front Street (it's to the left of the restaurant) and walk through the hallway to the handicap accessible entrance. This will put you in behind the greeter and give you a quick left-turn (toward the bathroom) to the Hidden Burger.