Orpingtons are possibly the most charming poultry breed I've ever kept.
I've never met an aggressive Orpington--not even one that was a little nippy--regardless of sex, age, quality, or apparent health. While hatcheries tend to mangle a breed's characteristics in an attempt to sell more birds (ie: allowing subpar specimens to breed), Orpington disposition has remained consistent regardless of which hatchery or breeder I've acquired the birds from. Particularly in the much lauded buff color, hatcheries will send out astoundingly poor specimens of the breed, and even these Orps typically have the most placid, friendly, non-aggressive temperaments.
My first Orp was a hatchery girl with an asymmetrical face (one eye was farther back on her face than the other, so she looked like two different birds depending on which side I was looking at. Weirder yet, her pupils were fixed such that one was always more dilated than the other) who was a terrible specimen of the breed according to conformation, but she had the sweetest temperament and was a bonafide lap bird every chance she got.
I've since kept Orps in other colors, from other hatcheries and breeders. They're an exceedingly charming lot. Roosters don't tend to be top guy in mixed flocks when they have to compete with other, more assertive breeds. They've often pretty chivalrous guys (especially if they're past that crazy hormonal stage or don't have much competition).
As a breed, they tend to be a very healthy lot, and the only health complaint I've ever had is that their tall single combs and large wattles tend to get frostbite. Mine never get sick, though some of the guys have been lazy bathers, so they end up with unwanted many-legged "friends". As fluff is profuse, some breeders have better fertility in hatching eggs after trimming excessive "butt fluff" for spring breedings.
They're overwhelmingly an easy breed to catch if they need to be rounded up for transport, medicating, what-have-you. They're typically slow and not generally scared of much so they don't run away like other, far wilier breeds. This is a pro and a con because, if you have a Fort Knox coop and run and/or no major predators around, easy breeds like Orps are great, but if you end to let birds fend for themselves over large areas unsupervised in areas with predators like hawks and coyotes, Orps are too dumb and slow to be your best breed for that job.
Another con is that, as a dual-purpose breed, Orps are an "eating bird", but I've never had it in me to process one. Mean, ugly, rape-y guys are the easiest to process, and Orps are overwhelmingly none of these. Big, fluffy, silly, sweet-natured, cheerful, friendly, guys who are good with their ladies are really difficult to process, so be prepared to fall in love with pretty much all of your extra boys and have a hard time saying good-bye to them.