I appreciate that most people posting on this thread are Croad Langshan enthusiasts but sadly my experience of them is very negative.
 
My neighbour bought 4 black ones last year after reading a magazine article promoting them. He bought them from a local breeder. He had previously had a mixed flock of hybrids and still has one of his original black sex links, Molly, who is now 8 years old and still popping out the odd egg.
The Croads are terrified of people, hardly lay any eggs and go broody repetitively. He was only interested in egg production, so they were perhaps not the best breed to buy, but he has averaged less than 10 eggs a week total, from 7 hens(4 Croads, 2 Light Sussex and the elderly black star, Molly) throughout this summer and as little as only 1 a couple of weeks. He is a real soft touch and loved his previous hens and would happily keep them into retirement but he is desperately disillusioned with his Croad Langshans to the point that he is actually considering culling them, something I never would have expected of him. He got them at 15 weeks, paid £15 each for them, and it took them over 3 more months to come into lay. In my opinion they are really ugly looking and have nothing going for them at all.
I even tried letting them brood some of my hens fertile eggs since they were so determined to set, but they are such big clumsy birds, they broke some and rolled others out of the nest and going back to the wrong nest after they had been out for a broody break, even though the other nest was empty! Partly, this was because they insisted on co brooding. 
My verdict is that they are totally useless birds and I wonder if perhaps this is the reason why they are rare.
My neighbour feels like he was conned by the magazine article. He is really sad that they are not friendly (they will not come near regardless of what is on offer) as his previous sex links were pets and he enjoys having social interaction with his hens. The light sussex he got from the same breeder are not much better but at least one of them will come and look if you hand feed Molly, rather than the Croads which cower in the corner when you go into the run..... I should say that they have a good size run and a big hen house and get to free range occasionally and Molly isn't a dominant hen, so there is no real bullying going on except occasionally one of the Croads will have a go at a sussex. His previous flock were a very happy lot. It's so sad to see these ungrateful hens taking advantage of his generous hospitality and accommodation and giving nothing back.