KRu points out what Jackson got right in the film.
Jackson "fleshed out" the characters, made the motive of using a burglar more credible, showed how Bilbo and Thorin's friendship led to both of them learning from each other, and made the dwarves into full blown characters (The Hobbit after all was a simple bedtime story, not a novel).
No, the Kili/Tauriel love interest is not an improvement.
I liked it, but it needed more background and interaction to explain why they were both outsiders with a lot in common and might fall in love...And only geeks know that Elves love only once in their lives, so once Tauriel chooses Kili, Legolas has no chance to win her heart, even after Kili dies.
Similarly, the story of Legolas' conflict with his father is hinted at but not given detail (uh, maybe Jackson should write appendices with this, as did Tolkien. A lot of the added stuff of the Hobbit film is in the Appendices of LOTR).
I should add that the Elf king was done well: consistent with both the books and the haughty elves of the Simarillion....