I think every restaurant should be like them. They have friendly staffs, quick service, good decoration that will make you think you're in a Nongjiale rather than one of the most luxurious area of Beijing (in a good way of course).
Food comes in reasonable price. The foods other than jiaozi is good too. We tried the dry-fried fish last time and loved it. Also the spicy vermicelli (sorry, I forgot the official Chinese name). This is the place I would go if someone visits me.
One thing I can complain about is their menu. They have too many varieties of dumpling fillings. I usually just let randomly pick 3-4 items.
But however, highly recommended! :)