Everyone raves about this place, especially people who live outside The Danforth/GreekTown, but it is pretty average compared to the overall quality of Greek Cuisine in Toronto and authentic Greek food (in Greece).
Kudos for their completely authentic Greek-style gyros, with the pommes-frittes inside the pita! However, the pita is too thick, and the meat inside is not much. The ambiance could be better. And their other food, except the gyros, is downright average. The price is right, but not super low.
There are plenty of places on the Danforth that are better than Messini's, both as food quality and authenticity, and ambiance. IMHO (in my humble opinion) as someone whose roots hail from the region and who has lived in Athens (Kiffisia) for a little while.