But as I said in my review of the first episode, I didn't like the ending when I first read the novel in the late 1950s, and I felt the same, maybe even more so, when I saw it on television last night.
[Spoilers ensue ... read on only if you've already seen the third episode, or don't care ... ]
We learn in the third part of the mini-series, as in the novel, that the reason that Karellen doesn't want Ricky and his current wife to have children is he wants to spare them the exquisite pain of losing them. This is an inevitable part of the literal ascension of humanity into a higher stage of evolution, in which human children become no longer children but the first expressions of this new species.
As such, this childhood's end is, in effect, a brief on behalf of children becoming liberated from and superior to their parents. I have no problem with that at all - in fact, it's already our way of life. But why can they never see their parents again - why is the ascension of the children mutually exclusive to continuing their relationship with their parents, aunts, uncles, grandparents, and adult members of their families? That's the part I've always had a problem with - first, as a boy in the 1950s, and now as a parent myself.
The reason in the narrative, of course, is that the Earth itself is ending. But why must that be? Why couldn't humans continue on Earth, even as their children went out into the cosmos as a higher power?
Well, Clarke wrote the story, I didn't, and he's more than entitled to write the story he wanted to write. And as I said, he did it masterfully, as did the makers of this mini-series. So, by all means see it, but don't look for me to recommend it and its profoundly unhappy ending.
See also Childhood's End 1.1: Familiar Territory ... 1.2: Losing My Religion