Pros
There's not much to say here, pretty much all Canadians know first- or second-hand what a Tim Horton's service/cashier job entails. Its a big name employer and their business has never shown signs of a slump, so at most locations the hours are consistent after you have spent some time there and if you do a satisfactory job. There is a always a chance to climb up to the store manager level if you have the willingness.
Kontras
Smaller, simpler orders, but very high volume and drive-thru pressure compared to the burger/pizza chains, especially if the store is on major intersections or outside highway exits. Breakfast hours are hectic. Also, the employee turnover is higher than at other places, so you get to work with a lot of different characters, which can be a pain sometimes.