Plenty of food places, the fish and chip one in particular is easy to find. We had some noodles at Excel for the Olympics which were woeful so we took our own food this time, but the fish and chips did look lovely although pricey at £9ish. The queues are OK too, the longest was for the decent coffee - there's not many coffee places although all of the food stalls sell tea and not-that-great coffee. Plenty of bars in the ring around the stadium but beer is £4.60 a pint - I think it's marginally cheaper if you buy it from one of the people walking round with dispensers (I think I saw £4.30 but may be wrong)
There are apparently a few smoking places, the only one I noted directly was by the food court in front of the stadium by the entrance from the aquatics centre (i.e. in trhe direction you'd walk from Stratford).
Oh yeah, and massive McDonalds.