Interesting novel, and a story that is, I think, impossible to tell with only one narrator. 25 years ago the author would probably have gone with 3rd person, but since this is the era of multiple narrators being far more prevalent than they used to be, multiple narrators it is. At least they possess very different voices. But there are too many of them, and the story is unnecessarily complicated.
At least one species of alien is suitably alien, however, and not just "humans but X."
I was amused by just how much NC comes up, for a novel that's set in space.
An extremely interesting novel, with a twist on the traditional storyline: Cromwell (the traditional heavy or villain) is our sympathetic narrator. It also features a *nasty* portrait of Sir Thomas More.
An interesting question is if Cromwell here is an "unreliable narrator" or not.
Note: "He" is almost always Cromwell himself, but occasionally it's someone else, so do read carefully.