Battlefield Earth would have been better as a 8-10 hour miniseries.
That is a LOT of pages to try to squeeze in to single movie, and they left out a lot of the character development.
It’s crap. The only reason the book sold more than about 10 copies was that The “Church” of Scientology made a concerted effort to force its members to buy 500,000 pity copies. It’s nothing but the pulp dreck that L. Ron Hubbard wrote at the start of his career; it would have been readable as standard 1930’s space shoot ‘em up, but when it was published in 1982 it was an embarrassment. It died the death it deserved.