I always associate this place with the airport in Madison; I always eat here either when I arrive or when I leave. It's a greasy spoon kind of institution, but done really well. As an example, biscuits and gravy is one of those dishes that's good just about anywhere, but Monty's manages to kick it over the top by including marinaded peppers or the like that give it a little extra flavor. All of the dishes are like that: fresh ingredients, nicely spiced and seasoned, etc. The prices are also very reasonable, so you basically get the low prices of a typical diner, but the food is actually really good.
Honestly, the only downside seems to be the wait for seating: I don't think I've ever gotten a table right away, but I can't fault them for being popular.