Honestly, the ending on screen is a lot less stressful than the pages. The book, right up until the end, is about the math, the jury-rigged solutions, the relentless focus on solvable problems. The film captures that, but the final scene—the big crew gathering around, the silent exchange, the music swelling—it's more of a pure Hollywood catharsis moment. Not necessarily bad, just a different flavor. The book's last line, about the decision to go outside and not do any math, feels more intimate, a quiet victory. The movie needed a visual spectacle to close out the ride, which works for a theater crowd, but the book's ending is true to that solitary, slightly absurdist tone. The heart is in the same place, but the wrapping paper is shinier.
I think the biggest shift is that sense of isolation. Watney's internal monologue is the book's core, and the film can't replicate that perfectly. So it makes up for it with a final sequence that bonds him back to the team in a more overtly emotional way. If you loved the book's nerdy, understated victory lap, the film version might feel a bit too polished. If you saw the movie first, the book's ending probably just seems like the same story told quieter.