Au Cheval was so good and definitely worth it! My wife and I were on vacation in Chicago and visited around noon on a Saturday. There was a short line to check in. We waited about 10-15 minutes, and then were given a 45 minute wait time. (We visited the book store around the corner, which I would HIGHLY recommend.)
We were very impressed by everything at Au Cheval, and it was definitely worth the wait. I see the burger gets a lot of hype, but it was honestly one of the best burgers I've ever had. We also got the bologna sandwich, which was great as well. The drinks menu was very impressive, with a pretty big and very good quality beer and wine list, and a cool cocktail menu which included some classics which fit the food and vibe nicely. There were also some interesting drink specials, and a bunch of unique items on the menu.
The service, however, was extremely good. The woman who was taking care of us was really really good-very attentive without making us feel rushed. She was giving the same great service to every table.
We would re-visit and wait in line to eat here again anytime. On our next trip to Chicago we will absolutely be back.