Second everything said above. Also, I think the second Hobbit movie is too violent for a 10 yr old anyway, IMO. Though the dragon was AWESOME!!!
After he reads The Hobbit and then the LOTR Trilogy, he can read The Silmarillion. My son read it when he was between 11 and 12 (only downside was the vampire and werewolf in the book) and it is wonderful for foundational information of the creation of Middle Earth, it’s inhabitants and the wars. He could actually see in the book the influence of Tolkein’s faith in the myth of creation of Middle Earth especially. My son understands so much due to reading it. In fact, it makes the current Hobbit movies more understandable since he knows the background and context that JAckson is incorporating. So although he definitely took some unfortunate liberties this time around, some things are actually accurate when it comes to what was occuring holistially in Middle Earth, if that makes sense. And in that regard, we like some of his contextual additions.
Bot of my children ended rading all four books (excluding Silmarillion) several times and they are only now 12 and 13. We love them all here.
edit: there’s a lot of movie critics here too and they must always read books first.