I went to the one here in Springfield 2 weeks ago. If you go, print off the coupon and at least get a dollar off. I had not been in quite some time, so I went for the entertainment, plus the weather was crappy. I didn't see any deals that I couldn't get at my LGS; ammo was too high, guns were high, etc.
IMHO, if you are looking for something special and you can get it on the web, it may be better to order it and have it delivered to the house. By the time you pay for your ticket, then the price at the show, it may be cheaper. Although, the atmosphere is entertaining! Kind of reminded of the summer county fair!