I'm surprised no other review has mentioned this: when the HOT sign is on, if you stop in you can get 1 free hot glazed donut per person in your group. Just ask. No coupons, no promo codes, nothing necessary. Got a family of four and the thought of picking up 4 donuts free and walking out: 1. embarasses you, or, 2. you realize 4 just won't be NEARLY enough? :) Then buy a 1/2 dozen and ask for your 4 free to go with it. They'll gladly oblige. Everyone's happy.
Great place to see your donut being made from start to finish. The machinery is pretty impressive! You can also catch them boxing donuts for the local stores if you're there at the right time.
In terms of size and taste alone, I do have a couple other shops I prefer, but with KK you are getting a certain experience that is unique and fun.