I’ll be honest: while I was prepared to allow significant leeway from the absolute MASTERPIECE that is The Lord of the Rings when Hollywood set out to do a movie adaptation (I simply assume that they are too incompetent to do an accurate portrayal), I lost most of my interest in the franchise in the middle of The Two Towers, when Frodo suddenly attempted to hand the One Ring over to a Nazgul.
That being said, I have now watched all six movies in this franchise, and all of the Hobbit movies make that moment look like it was directed by Tolkein himself. The Battle of Five Armies is simply painful to watch–from the the simultaneously tedious and extraneous dwarf-elf romance, to the inept battle-tactics (The Dwarves set up a huge, sturdy shield-wall between a host of Elven archers and the oncoming Orc army. What do the Elves do? Jump over the shield-wall and engage the Orcs hand-to-hand!), to the continuation of a huge error from the first series (Why do the Elves keep DYING? ELVES DON’T DIE.), to the just plain stupid (“These bats were bred for one purpose. War!”).
The makers of the Lord of the Rings series made its tone significantly darker than the novel ever was (it is actually a single novel), and now they have made The Hobbit–a childrens’ book!–just as dark. Further, they have padded and stretched this much smaller work, to the same film-length as was taken up by LOTR. It’s like watching butter… scraped across too much bread.
Update: Here is a link to a review who is much kinder to the LOTR series than am I.