Short version: Be wary of the opinion of anyone who gives Jack Astor's anything above a 3 star. It means they're either easily impressed, or they're possibly an employee. Even 3 stars is generous, because J. Astor's is the culinary and customer service equivalent of a limp handshake.
[rant]
We ended up at Jack Astor's because it was late and my companions mentioned that it was one of the restaurants that would still be open. It's very busy; having now tried it, I cannot for the life of me figure out why. I got the Señor Jack's Jalapeño burger. The menu description mentions jalapeños three times and also mentions hot chili sauce. Yet, it tasted like it was drowned in sweet relish. It was poorly made, messy, cold, and a terrible burger in every sense. It was also $14.00. I don't know if this is normal for you Canadians, but that's some serious bamboozlement if you're spending $14.00 for what is no better than a burger from A&W. Actually, that's an insult to A&W burgers. My dining companions got the Hold the Beef Burger, and the Cluckin' Fresh Chicken Fingers. The HTB Burger got a shrug, and the Cluckin' Fresh was Cluckin' burned (burnt for you lovely Canucks).
Service was practically nonexistent. We saw our waiter lady person when she took our order. After that, she vanished. She wasn't even the one who brought the food to us, and she never once checked on us during our meal. We saw her again only after I started snapping my fingers (like only a rude American would) in the hopes of getting the attention of someone so we could get out of there. Then she hovered while I paid and calculated how much to tip for the terrible service. Is that a common thing by the way? Standing there and waiting to see how much you get tipped?
Meh food = "Meh. I've experienced better." Throw in the ridiculous markup on the aforementioned meh food as well as the incredibly sub-par service, and dropping the rating to "Eek! Methinks not" seems very appropriate. Jack Astor's is an appropriate name, because I felt like one for dropping $50.00+ at this establishment. Considering all of the amazing dining options you have in Toronto/Mississauga, there should be no reason you end up here. Even if everything else is closed, go to a grocery store and slap something together using random ingredients and I can almost guarantee that it'll be a more satisfying (and significantly cheaper) experience. Go here if you want to end your night with feelings of regret and frustration.
[/rant]