I saw this only recently and agree with the view that the personalities were honed as the series developed. However, I was surprised at how clumsy some of the writing and acting was. Lorne Greene and Pernell Roberts in particular were very stilted and looked uncomfortable in their roles. The only one who really hit the ground running was Michael Landon but that may have been because his part was better written. The characters of Ben and Adam were one dimensional and crudely drawn. In this opening episode Adam is no more than a disapproving older brother who clearly resents his younger brother even going as far as to insult Little Joe's mother's background in New Orleans. Ben is a bullying blow- hard who snaps out crude orders to his sons and threats to opponents. Little Joe is headstrong and wild but also a charmer. Hoss (not a bad performance Dan Blocker) is shown as a reasonable counterpoint to his father and brothers, adopting a far more fatherly approach than Ben.
It is just as well that both acting and writing improved or I doubt it would have survived 1 series let alone 14.