Towers burger kitchen isn't too bad really (I should know, my parents insist on eating there every time we go). Its far from the best food I've ever eaten, and towers can do much better, but in comparison to other parks, it's not the worst. We ate at burger kitchen at chessington yesterday. Burgers looked like they'd been kicked around the floor, so much so that all three people in my group who ordered burgers had to send them back. We had the response "we can give you new burger, but it will probably be exactly the same, my best advise is to take a refund and eat somewhere else".
Hard to beat that customer service.