I really liked this show, growing up it was one of the few things my mom let me watch that wasn't on PBS kids or something. Though I can see everyone's point about the historical inaccuracies, I think we all have to remember that it is a TV program, and things have to be dramatized sometimes, for the sake of ratings.
I personally thought the casting was well done, and especially appreciated that, even though Michael Landon was such a great and popular actor at the time, he never outshined the kids. When it was their time, he let them have their scene and never tried to steal the lime light.
Though on the other hand, some acting left a lot to be desired (Such as that of Melissa Gilbert and Lindsay and Sidney Greenbush in the later seasons) I think the family dynamics were well-kept and properly nurtured. It was great to kind of go back to a time when morals had a strong influence on society and people were neighborly. Those are things that I think a lot of people miss in today's society.