If you are already planning on eating at a table service restaurant, then I would say it is worth it. Otherwise it is not.
Lombard's is similar to a Ruby Tuesday's or a higher quality Applebee's. Nothing special, but still pretty good. The way the dinner show works is that you eat dinner at just about any time that you'd like. You get an entree and I believe an appetizer. You don't eat dessert with your dinner. They give you a ticket and you can come back about 30 minutes before the show starts. They have a dessert table, soft drinks and coffee, tea & hot cocoa. You eat dessert out on the deck while you wait for the show to start.
It is a nice event, but I wouldn't consider it a must do. Like I said - do it only if you want to eat a sit down dinner at US.
I would guess no since it is a premium price vs the normal cost of dinner. But that is just a guess, so I can't tell you for sure. Hopefully someone else can chime in here.