I'm partway through Dead Man's Walk and it's held up well so far. Streets of Laredo was tough at first but by the end I found it enjoyable overall. Still, I'm not sure how much of it was McMurtry being willfully antagonistic to readers with the decisions he made for the plot based on how well received Lonesome Dove was.
Dead Man's Walk was the best of the rest...but it even it was flawed, with all the brutality of Lonesome Dove without the beautiful interstitial moments.
One of the prequels (Comanche Moon) is actually quite good and featurs more Gus and Caul banter