If I had a better method of traveling between cities at the same price point, I would make the switch without a second thought, that being said Greyhound is the only choice of budget transport to get to Kitchener-Waterloo.
The Toronto Bus Terminal is one of the better bus stations I have used in North America, It has great access to the city centre and is clean and secure.
The service in the terminal is good considering how sparse the station is and the number of staff that are on the front lines. That being said, the service provided by Greyhound over the phone is absolutely horrid, unless one speaks to a human service agent, the phone system is useless.
If you can I would recommend purchasing your ticket online and printing it out yourself to both save time and money as there is a facility fee at this location to the tune of ~$2.00.
I really wish that Coach Canada and Greyhound would take the time to evaluate customer feedback on the operation of this facility as the current queuing method for the buses is ridiculous and downright dangerous.
2 stars for being an affordable choice of travel, however if there was a comparable alternative this score would probably drop by a half star at the least. Compared to other major (global) cities, Toronto suffers from a plethora of poorly planned, built, and operated facilities for mass transit.