They made the Amalekites super dark and scary to the point my 5 year old was scared quite often. They're also frequently recurring throughout the movie, so it's not just a cover the eyes and be done with it scene. My kids are pretty sheltered from scary content, but under 6 or 7, I'd probably steer clear.
Oddly, on the other end, they softened David up so much that he would have been at no risk of not being able to build the temple or anyone singing about his slaying anyone, much less more than Saul. I'll stress that they took a whole lot of license on this point.
His interactions with Saul were all pretty right on, and his message of faith and fear of God alone were the strongest part of the movie and very solid. The music was good but not super memorable.
Overall, I love the life of David and really didn't care for the movie. My 8 year old who knows his Bible was even calling out the differences. It's not a bad movie but meh.