There are multiple Plaza Premium Lounges in YYZ, depending on which terminal you're flying from. They all have the same basic concept - comfy chairs, decent food and free WiFi. While there's nothing special about them, it's nice to be able to kick back if you have a few hours to kill before your flight.
They have a decent hot counter with breakfast (sausage, eggs, bacon), lunch (usually chicken/beef and rice/potatoes). The food is decent and plentiful, if like me, you hate eating plane food. This location also has a full bar which is included in the price. It definitely beats reheated cardboard and overpriced booze on a plane.
Some credit cards allow free access, but you can also buy a pass for a reasonable amount ($30-50) depending on how long you're staying. A solid three stars, nothing outstanding.