Right off the bat - when someone gives you the ol "Happy Dog has the best hot dogs ever!", it is a coded way of saying "I love make-your-own-salads they're so fun!" That's basically what people like about it - the 50-some topping options. The hot dogs themselves are a cheap, tasteless, bottom of the barrel canvas, and the bun is even worse.
The food quality hints at twice-a-week GFS runs. Beer selection is relatively average. The atmosphere isn't bad. They used to have good live shows here, but I haven't had a reason to go here in the last couple of years.