I've been to the one in Orlando twice and enjoyed myself both times. It helps to go on a busy night when there's a lot of cheering going on. They seat you in sections and each section cheers on one of the knights through a tournament (for various reasons and with various story plots that change over time). Incidently, my knight won on both occasions
Overall I found it to be a great experience. Both the knights and horses (and a hawk!) have undergone significant training to put on the show they give, and the food was awesome. However, it's also very expensive... I certainly wouldn't go more than once a year or so. Half the fun is also buying stuff in the various shops and they take a picture of you and your date (assuming you have one

) on the way in and then stick your face on a knight and lady picture and try to sell it to you later. It's fairly well done, though.
So, to sum up a recommendation: awesome show, great food, take lots and lots of $$ if you go.