Don't go expecting too much.
Think of it as a type of bar in the stadium cause that is all it is. You can get pies and povrils as such like you do at the kiosk and then they usually have a meal type of thing like chicken curry, haggis needs and tattles or something else. They have just started doing a chicken box as well where you get a couple of bits of chicken and some sauce, type of KFC thing. If you want a drink and pie at halftime buy a token as said, no alcohol is served at half time.
There is a few tvs to watch sky sports before and after, but that is it really.
Main thing it is good in the winter as you can go up at half time into the warmth.
Just to add you do not have to buy a token at half time if you want food, you can still get food and drink without a token at halftime. They usually have a bench away from main bar where you collect your stuff with your token, it is supposed to be quicker.