This is a colonization novel, and a Quaker novel, but any similarity to The Dazzle of Day is fairly superficial. It begins in media res, with the colonists thoroughly planted on Pennterra, and already firmly in contact with the native hrossa, while the other ends as the travellers reach the surface of their planet. Another dissimilarity is that Pennterra has many characters who aren’t Quakers, and the cultural dialogue between them enriches the text – though it would have been interesting to have seen someone cross over properly, or even be in much doubt about their position.
The book was written in 1987, and it shows in the future it depicts – Earth has been ruined, worn out, broken. The overcrowded population are starving, living on algae cakes, so presumably everything went Malthusian. And mass colonization of another planet is still a real possibility. The irresistable comparison, for me, is Anne McCaffrey’s >Decision at Doona, and that was from 1967, so it’s almost certainly an influence.
As regards themes, it’s mostly about food, and sustenance, and how to keep right relations with the world around us. It’s a constant ethical quandary for Quakers and other thoughtfully spiritual people, and this book gives an interesting perspective on it. I don’t think it’s a story that only SF could have told in the same way that The Dazzle of Day is, but it’s still a very good and powerful one.
The Quakers – all scientists – gradually find out a lot of the way this new world works, and find clearness on the restrictions the natives have placed on their expansion. On Pennterra, there are no predator/prey relations; all consumption is a gift. This is… not an easy thing to get used to, even for the Quakers, and we see quite a bit of their bitterness and resentment at being casually denied the future they were expecting.
Moffett does a good job of showing us how they find the nature of the planet out, mostly by giving us excerpts from their diaries-cum-informal-lab-notebooks, making no distinctions between biological research, botanical studies, practical anthropology, and conversation between friends. At the same time, we see the characteristic painful Quaker honesty about themselves and their reactions to their work.
The pacing of discovery is good, without playing I-know-something-you-don’t-know tricks on either reader or characters; it might have been good to have seen the author coming down less heavily on the Quaker side, but then I may well be seeing more of that than there is there as a Quaker myself.
 Which isn’t the same as a colonial novel; nor is it a postcolonial novel. It’s an interesting beast all of its own. There are some problematic aspects to casting humans as the colonizers (though they’re explicitly multi-racial) and aliens as the colonized party, but otherwise it provides a very interesting vehicle to look at huge differences in cultural practice and needs.
 A deliberate in-universe reference to CS Lewis’s Cosmic Trilogy – the hrossa there are natives of a planet whose people did not Fall.