I took my 5 year old nephew to Medieval Times last night and he had a blast! He got right into the show, cheering at the top of his little lungs for 'our knight' and waving his flag constantly.
The meal is quite reasonable - definitely lots of food. My nephew loved the chicken and thought it was quite fun to eat with his hands. (I took a pack of wet wipes which came in very handy). Server was fantastic.
Definitely recommend Medieval Times for a fun evening out, especially with kids.