How can The Desolation of Smaug fail on so many levels?

Rating: 3/10 (16 December 2019)

I recently started reading the LOTR series, and though the books are not mind blowing, they are very good. I enjoy them a lot also due to a fact that they explain what was sort of unclear in the movies - interesting details or things that make click in the head and allow you to see the whole picture. And although the movies lacked those here and there, they followed the books very closely and did the source material justice, to viewer's benefit.
Now I can't judge Hobbit the same way because i didn't read it yet, but I suspect that 300 pages book isn't enough material for 8-9 hours of screen time, and this is how the second installment feels. I found many parts of the story unnecessary, like the politics in the lake town, skirmish with orcs on river banks and honestly also Gandalf's quest in Dol Guldur. The quest didn't reveal anything new about the Dark Lord; on the contrary it presented him (and the whole place) in pretty underwhelming fashion.
The film tries to keep you on the edge of your seat with never ending action and ubiquitous dangers, but it fails miserably. The fellowship always survives, no matter the situation, and I am not even talking about elfs being invincible ninjas. It is clearly established that nothing can happen to our heroes, so the opposite of suspension is actually achieved.
The CGI is somehow worse (maybe from overuse?) compared to LOTR and together with the endless bombastic action the movie feels like video game, which isn't good.
It also tries too hard to capture the magic of the original movies by showing familiar characters and objects. Thorin is another Aragorn, but with less charisma and not many likable characteristics. I felt really bad for him when he had his speech in the Lake town about how he will share the gold from Lonely Mountain ... and not much else. The dwarfs are another fellowship, but much less likable? The whole company seems to use Bilbo rather than treat him with respect which doesn't make sense - he saved them all multiple times. I am really curious how it is in the book, but here I couldn't care less about any one from the company due to how they behave. Then Gandalf - he had such presence in originals, but here he is just a shade of himself. Legolas is completely different, jealous, always serious looking killer without traits. And Bilbo has barely any dialogs going for him, which is strange for a Hobbit movie. And there is of course the Arkenstone - the Ring overloaded. I don't know how much from those was in the book, but maybe it would have been better to separate itself more from the first trilogy.
Reading reviews here I am surprised nobody mentioned music. It felt off in many places, like when in the Lake town they found that they lack on good weapons and are spied upon. A dramatic, urging music goes off but nothing is really going on on the screen, no danger is approaching.
Last but not least, the ending is, mildly said, over the top, but what disturbs me the most is that the dragon just flies away after they pour gold on him. What kind of plan was that? To make a huge gold statue and drown him in it once it melts? Not only wasn't this plan ever discussed, it is just plain stupid.
To summarize, I am actually glad that I have seen the movie, because it makes me want to read the book pretty bad, but in and of itself, the movie is really bad.