I've only walked past it without checking the lineup (thinking to myself "huh, a beer bar at Pearson"), but pictures and descriptions suggest they have multiple Muskoka beers and GLB Canuck on tap. If you have time to kill and are in the mood for a beer, it's probably at least worth checking out, but I wouldn't expect to see any rarities on offer.
"Bar people do not live as long as vegan joggers. However, they have more fun." - Bruce Elliott