Black Stars have been the highest producing hens in our homestead flock, with the exception of leghorns and leghorn crosses. No other brown-egg layer has been as productive for us, with Barred Rocks probably taking second place. Eggs quickly get past the "pullet egg" size, and move through large to x-lrge and jumbo. Hens are large, with massive crops, stout legs and strong feet. They take very well to free-ranging, energetically rustling for their own feed, but they are not averse to gorging at the feeder. A mixed bag of personalities, some high in the pecking order, and some on the bottom, but all docile and interactive with humans. Hens laid year round (15 hour light regimen), and most of the time would lay where they were supposed to. The birds were alert to predators, and have good coloring to avoid detection. As hens reached their 1st birthday, it wasn't uncommon to see the occasional soft-shelled egg, not unusual for a bird with such high production. (These birds have free choice access to calcium). Molting speed varied.
Hens went broody and raised chicks for us more than any other breed or breed cross we have had. This was rather ironic, since we were told the BS's were commercial-level brown egg layers, and did not go broody. Even more ironic was that we were raising Buff Orpingtons at the same time, a breed known for broodiness, and not one BO went broody! BS's, being large birds, can cover a lot of eggs (one hen hatched 12 eggs).
BS carcasses were fat, with a decent amount of meat (more so than the purebreds in the flock). Hens seemed to break down early though, with several becoming internal layers and others dropping production level as they became very fat. Perhaps these birds do not do well on free choice feed? Or maybe high production burns them out earlier.
For me, the biggest negative with Black Stars was the noise. Hens are extremely vocal at laying time, with loud, penetrating squawks and clucks before and after laying. It was annoying enough that once we culled them all out, we have not gotten any more. A hen house and nest boxes well away from the house would make it less of a problem.