I remember having read this in 3rd or 4th grade and having liked it. Basically, we have the autobiography of a horse. Black Beauty, it seems, is a stallion (or gelding, we're never told). I always assumed that with a name like that he was a she. But nope! A guy horse. None-the-less, all the 9-year old girls who love horses will adore this book. So, also will old Calvinist moralists, like myself, who like animal stories dosed with some good, old fashioned moralizing.
Anyway, this was quite a fun book. Beauty narrates his life from colthood to old age. He sees many changes in that he switches hands from time to time from a good "master" to a not-so-good one, from good care to negligent care, from proper work to over work, and so on. Along the way, we learn the stories of some of the other horses with whom Beauty shared a stable, and we learn much about the proper way to care for a horse so as to get the best work from him. Horses like to work hard for people they like. Nope, don't mind it a bit. Bless their equine hearts.