I only know enough about Joe's to know that the burgers are delicious, and that they're half off on Tuesdays, Thursdays and Saturdays. I almost always get the Loaded Potato burger, which is great, and their fries are amazing. Occasionally the service is really, really slow, which is a real pain in the neck, but it's not a regular problem. Their drink specials are also pretty good, on par with the rest of Campustown.
As long as you treat Joe's like a den of vampires (avoid after dark), it's a nice restaurant.