A flat-out dive, the Original has been on something like a dozen Travel Channel/Discovery/PBS/Food Network shows because it does two things very, very well: Hot dogs and french fries. Sure, there's pizza and subs and such but why would you chose those over the superb dogs and taters.
The fries are legendary: tasty as hell and absolutely huge servings. Amazingly large. Shit-ton large. Order a small unless you're sharing. Period.
The dogs are really good, with a great variety of toppings and other variations. Just great.
So, if I like it so much why the missing star? One word: dirt. It's known as "The Dirty O" and that's a well-earned name. There's a decades old patina of cooking grease on everything, and while I don't have a problem with it, chances are someone in your party will and will make an issue of it. But if you can get past that (and keep your food on your tray) it's a five-star place.