I saw the first Hobbit movie in HFR (high frame rate which is 48 fps vs 24 fps) and was a bit disappointed because it looked too real which gave it a kind of soap opera / BBC feel. The 2nd Hobbit is similar. I saw it in HFR also and felt the cinematography was slightly better, but it really needs something to give it more of a film look.
What stood out most to me was that, more than any movie I have ever seen in the theaters, this one leaves the audience hanging at the end on almost every plot line... the dragon, the town, the love triangle (not in the book as you mentioned), Gandalf. It almost seemed like a TV serial other than being nearly 3 hours long. The first Hobbit had a great stopping point at the end in which the tension of the story was resolved, but the audience’s expectation is set for coming adventures. In this one, very little of the story is resolved.
One negative that stood out to me was the love triangle involved a brief sexual innuendo that seems quite out of character for a Tolkien story and for the targeted family audience, particularly because it came from among the ensemble of heroes rather than a villain. Not a major issue, especially by today’s standards, since worse happens all the time on prime time public programming. But it was still a little disappointing as it deviated from the spirit of the LOTR series and Tolkien in general I thought.
But I still enjoyed it over all. And I actually like the embellishments that flesh out the characters and the world they live in.
My son pointed out some of the deviations are from the Silmilliarian. I haven’t read that in a long time.