NO SPOILERS!
Let me start by saying I've never read the books. However, I know a friend who did and she recommended me the movie. So I watched it, being interested from the trailer.
First of all, great actors. A lot of the people I know argue that Sofia Wylie wasn't the best actress for her role, although I've never read the series so I can't say anything about it. I think Sofia did quite well, along with the other actors and actresses!
The plot is interesting as well. I'm not one who's into fantasy, but this movie has gotten me interested right away from the beginning and it has until the middle. However, after the climax, it slowly started to not make sense. It just feels like they planned everything and after the climax, they just made up everything as they went. It made me question a lot of things too.
But this movie was overall silly and enjoyable. I recommend it for ages 12+, because there is VERY mild swearing, some blood, jumpscares, action, etc. There are also a few scenes where they use knives and arrows, but nothing too gory.
Enjoyable movie when you want to kill some time! Enjoy!