Hmm, I want to like this place more, but it's just A-OK in my books. It's a good alternative to the coffee chains (Second Cup, Starbucks, Tim Horton's) in the area, however I think Kensington has several far better choices, or there is a TAN Coffee on Baldwin close by as well.
Sonic is cozy and laid-back. The service is good and it's a comfy place to hang out with friends. The picnic table is a great spot in the summer. It never seems to get too busy. Since it's on a side street just off Spadina, a lot of people probably miss it. However, I have never really been too impressed by their drinks. Both their iced lattes and hot chocolate taste watery and bland (they do have liquid sweetener though, which is good). I would stick to their hot espresso-based drinks. Prices are good, but the sizes also run small.