Being from Indiana, this is only the second time that I have ever been to a Harvey's, and the first time that I ordered something other than poutine (although I did order poutine). The burgers were actually pretty great--they tasted more like something you would get at a back yard cookout and less like the fake stuff that you would get at your neighbourhood McDonald's.
Though the outside looks pretty dated, the inside is fairly modern. They have a Pepsi machine that is reminiscent of the Coca-Cola Freestyle machine (the touchscreen fountain dispenser that can customize drinks with cherry/vanilla/etc. syrups).
The employees that were there when we came in were friendly and quick and attentive to their jobs.
Overall, for the value, this was a pretty good place to get a good, quick meal for a fair price. We'll definitely be back the next time that we're in Mississauga.