I discovered this place years ago, because my sister lives just up the road. The Danforth offers so many incredible Greek restaurants that the rather non-descript Zorba's is often overlooked by those not familiar with the area, and that's rather tragic. Fact is, Zorba's offers excellent food for a lot cheaper than the more "posh" options further west. I'd put their lamb souvlaki on par with Astoria easily, and it's a few bucks cheaper.
This trip, though, I had the lamb shanks that are on the steam table but not on the menu - they were absolutely incredible, falling off the bone/melt-in-your-mouth quality. For the price, I doubt you could do any better. Generally I'm there in with a big enough group that their group options are better go, though.