The falafel, shawarma and kefta are the classic, fast-food staples of Mediterranean cuisine and Jack's has nailed it. The hummus and Jerusalem salad have just the right amount of tahini and the food is cooked to order. No dry or overcooked falafel. This spot is the jammy jam for this kinda food in Champaign!
Don't plan on being impressed by the decor in the place though... there is none. That doesn't bother me at all. Jack's feels more like my friend's house and their parents keep offering me more food..."Eat! EAT! Try this. You'll love it! You want some more baklava? Here, take three pieces."... and I like that.
My only complaint: I wish they were open late.