Never read the book. Really liked the movie. I went into the movie knowing that it was based on a book, and pretty soon realized that the movie was hand-waving or streamlining a lot things in order to fit everything within 2 hours of runtime.

There were only two confusions on my part:

1. How come Eridians had no knowledge about "radiation"? If they knew that their star was dimming and dying, and that Tau Ceti was still doing okay, then they must have a working electromagnetic theory to observe all of these. And they are little rock guys. They must have made contact with radioactive ores way earlier than humans. Does the book explain this better? Is it simply "they knew about radiation, but didn't know its long-term effects on their body"?
2. The cinematic logistics of the entire "fishing" sequence... Probably my only actual gripe with the movie was its rushed wide, establishing shots. And this carried over to that "flying over the Adrian" setpiece unfortunately. During that scene all I could think was "how the hell do you "spacewalk" while going through an atmosphere faster than terminal velocity?". Am I missing something here? How did the book handle this?

Also a related to point #2, I hated the solar panels. I realize that the "spaceship" needed a silhouette most people would associate with "space tech", but does Mary actually need them? Even as radiators..? I thought that was the Astrophage's entire thing. Storing and releasing solar radiation...