I recently visited Duo (again), and let me just say - the pastries are absolutely delicious! I especially love the yuco and pastiche. The pricing is good (starbucks price), the location is rather convenient for me, and the the workers are lovely. They're polite and friendly. I think the only factor that was a little disappointing is that I went at 4:00 on a Saturday, and there was barely anything left! The pistache's ran out, there were no more macaroons, and there was only one yuco left. And the person in front of me bought it before I could!
But that only shows how good the food there is!
If you go on a Saturday, I recommend going before 2:00.