I have three Buff Orpington hens in my flock and they are an absolute pleasure to own. I really love their build and size...they are a heavier bird, and their chunky structure shows it. Because of their size, they are pretty bad at flying, which is an added bonus if they are confined to a backyard or urban area. The birds are very winter hardy, as their combination of fat and fluff/feathers keeps them very warm. My Buffs were wandering around the yard in 10-15 degree temperatures and were completely unaffected. They are also rather intelligent for a chicken. They have great foraging skills and are not picky when it comes to eating. They will pretty much eat anything that they can swallow, which helped me save on feed. I always offered them layer feed inside the coop, and when combined with free-ranging, they seemed pretty efficient for their size. These birds are also quiet. They don't make much racket like other chickens, and only really cluck when I come over to them, otherwise they are very relaxed and calm in the yard. My coop is oversized for the number of birds it holds, so I cannot say with certainty that they take confinement well, but my birds seem plenty happy in their house when they are not/unable to free range (like when there is 12 inches of snow).
As for their egg laying, I can say that I am fairly unimpressed. Some reviews say that they are great layers, and some say they are average. I would fall into the average column. My orpingtons took the longest to start laying...two began at 24 weeks, and one began at a few days ago, at roughly 8-9 months. Two lay a medium-sized egg, and one lays a large/XL egg. They lay anywhere between 3-4 eggs per week, and usually drop an extra day in the winter. I was under the impression that they were more prolific layers (and my expectations were high as I have RIR and Sex Links that produce a ton of eggs), but I would classify them as average layers. I believe that the egg size will increase as they get older, but I highly doubt that the production out of them will increase. The one orpington lays a freckled egg, which is an added bonus though!
One of the cons (which is easily fixed) is their identical appearance. Now I know many chicken breeds can look identical, especially the sex links, however these birds are just incredibly similar. Their personalities, shapes, and habits are all identical. I call mine the triplets, because naming them would be a lost cause. I will put legbands on them in the spring and officially assign their names to them. This is more of a petty concern, and not a strike against the birds. I would love a flock of only orpingtons one day, because they are easy to own, relatively productive, and really fun to handle and watch!