The Second City amounts to a great night out!! Their comedy acts are top notch put on by some very talented comedians. Second city alumni from other cities go on to become big names, and while the most I've seen of the comedians from the Toronto cast are on TV commercials, I wouldn't be surprised to see them move on to bigger stuff from here on.
The tickets are not very cheap though if you buy them just like that, keep an eye out for discounts and if you get a group together (or student pricing I believe) the costs do come down and it's worth every penny.
The times I've visited, I've sat in the very last row as I came with a group for my birthday after dinner at Gretzky's and while we were the furthest away, the view and experience did not suffer. We hung around for their audience interactive improv after the show at which point we were able to grab seats all the way at the front.
Food and drinks are not cheap, not very overpriced at the same time and from what I remember the food was actually good, and their menu has a nice variety of finger foods to "proper" meals.
All in all, a great experience and it's a lot more family friendly than stand up comedy around the city.