I've just finished the last of the Red Sparrow series, The Kremlin's Candidate, by Jason Matthews. The last half of the book was a real rollercoaster/nail-biter. The book had more description and less dialog, especially in the first half, which left me a bit impatient. The ending was good (appropriate to the situation) but it left me feeling sad, haunted, almost like being in mourning. As your read the series, you may find yourself hoping for the best, fearing the worst. The series ending is a mix of both.
A word about the movie: Again, it was good, but did not strictly follow the first book. Jennifer Lawrence was excellent. The critics were right about a passionate spark being missing between Dominika and Nate in the movie. A shame, because that passion was a major force in the books, especially the first two.