When I first began Kilimanjaro, I was worried it was just Kirinyaga, Take Two. I enjoyed Kirinyaga but felt no need for a repeat performance. It turns out that I was right but for the wrong reasons. Kilimanjaro stands apart from Kirinyaga, with different themes even if it has a similar setting.
The main character, David, seemed just as arrogant about the superiority of Maasai ways over Kikuyu ways as Koriba was about the superiority of Kikuyu ways over European ways. David is remarkably naive for a historian, constantly espousing optimism even when it's obvious that the situation won't turn out well. Rather than being an obstinate mundumugu who insists that it's his way or the highway, David is an open-minded historian who looks to compromise for solving his problems. This is an important difference between the two protagonists.
The juxtaposition of a desire to maintain traditional lifestyles in the face of increasing urbanization and assimilation that worked in Kirinyaga returns in Kilimanjaro, to good effect. The Maasai attempt to learn from the mistakes made on Kirinyaga. They know that returning totally to a traditional lifestyle is impossible, that the "damage" has already been done. Nevertheless, there's still a sense that a certain erosion is happening, as seen in the story with Sokoine the laboni. Even though the role of the laboni over that of the doctor remains paramount on the manyattas, Sokoine finds more and more pastoral Maasai opting for hospital care instead of witch doctor care. Similarly, toward the end of the book, Kilimanjaro opens itself up to tourism in an attempt to make its big game park an economically self-sustaining entity. But as David explains, tourism means the need for tourist accommodations, tour guides, space ports (and gift shops!), banks, etc.
The message is not that traditional ways of living are doomed but that society is always changing (although the former may follow from the latter depending on the nature of that change). We can't always control that change. Even we do manage to direct it during our lifetimes, there is no guarantee things won't spiral out of control when we are gone. As Blumlein puts it, "Utopia isn't the end result at all, but rather the simple act of striving for that result?" Hence, Kilimanjaro rather baldly states its theme. It is not as subtle (nor as ambiguous) as The Dispossessed in its analysis of utopia, but that makes it no less worthy a book.
Resnick explores what happens when cultures collide, especially along generational and gender lines. I'm torn, when comparing the two books, whether I prefer Kirinyaga or Kilimanjaro. The latter does feel like a repeat, but I prefer its protagonist. On the other hand, Kirinyaga had better stories. Koriba was quite clever when in some of his solutions, and watching him execute a plan was a pleasure. David, in contrast, tends to sort of stumble through his conflicts, trusting on the rationality of people to result eventually in some form of resolution.
So I think my conclusion is … read both. They're really the same book, or two halves of one book, the Janus of utopian literature. Kilimanjaro makes you think differently about Kirinyaga than reading the latter just on its own; vice versa for the former. I can't say much for Resnick's ability to create characters or compelling plots; neither of those things are present here to any great degree, and these are the only two books of his I've read. He does know how to put science fiction to good use though.