I have never left Open City disappointed. Any time people visit me in DC and brunch is on the agenda (why wouldn't it be?) we always return to the same place. The only flaw I can think of is the Sunday morning wait, but the good news is that you're waiting for great food, good service, and an all-around positive dining experience.
Open City is open for all meals, but I prefer to go for brunch. The juices are fresh, the pancakes are yummy, the eggs are tasty (my favorite - Blanco Scramble), and the atmosphere is jovial. I have had dinner there only once, with a big group, and while Open City is Open City I much prefer to pay them a visit in the late morning. The ideal time is 11:00 am.
As a college student at American University in Northwest DC, Open City is not far at all and my friends and I know we must pay them a visit often. I feel bad for DC students who don't live close to Open City, because I have friends who have never even been there. They're missing out. Bottom line - the brunch at Open City is to-die-for, my personal favorite. Come hungry.