I also agree.
The LOTR movies, the uncut versions, are superior to the books. At one point I counted it out and Tolkien spent easily 2 pages describing Galadriel's hair and how it was perfect. Thats a shade excessive. (although, I seriously am peeved at there not being a Tom Bombadil in the movies. I'll grant you that it makes sense though)
To expand upon Mr Owls point though, if you were to take the Hobbit book and rip out the extra bits where Tolkien, you'd have somewhere around a 200-250 page book. Not really sure where that warrants about 9 hours of movie. Hell, it does't take 9 hours to read the hobbit as it stands right now.
But anyway, here is my list:
When Bilbo finds the ring, its merely a trinket, its just some bit of treasure, there was no foreboding sense of Evil/ doom around it. The Arkenstone. Why was Bilbo able to find it, not once, but twice, in a treasure hoard that literally filled the main hall of Erebor and then some. All while Smaug sat there and ran with his villain monologue. Mirkwood - all of it was just wrong, and far to fast. It was (I believe) 3 chapters in the book, but its like 10 minutes in the movie. Mirkwood was huge, and honestly, they should have dropped the Barrel sequence and added more to Mirkwood. Mirkwood Spiders - Bilbo kills a spider by dropping it to the ground. Then he turns and cuts the dwarves from the webbing, they drop to the ground and live? If its high enough to kill a spider, its high enough to kill a dwarf. Tauriel - nuff said Legolas - Nuff Said Love Triangle - it was forced, for literally no reason. Elf super powers are insane. Okay so I get the Elves are badasses, that makes sense, but Tauriel might as well of been Wonder woman for some of the crap she pulls in the movies. Legolas was nothing compared to her. Eagles - The Maiar Eagles only flew Gandalf and the dwarves halfway to the Lonely Mountain. Tolkien never explained why the Eagle lords wouldnt' fly closer, it was always left as some nebulous reason. Smaug's sense of smell - Smaug wakes up because he smells Bilbo. Even though he cannot see him. Then, all of a sudden he can't smell the 13 dwarves that climbed through a toilet to get where they are? All the Orc crap more or less - Seriously, Azog was completely unnecessary I can sort of argue for the White Counsel, however, it was added in the Appendix and wasn't part of the original book. Orc fight in LAketown Dragon Hide and Seek/ Molten gold attack thing Barrel fight...... honestly, what the fuck. This sequence felt like it was 2 hours long Gandalf see's Sauron at the Nazgul Tombs?????? Really? And then he has a showdown with him????? So what you are telling me is that before LOTR happens, Gandalf knew the significance of Bilbo's ring, knew Sauron was coming back, and that Saruman was evil? And then he just fucking forgot?????? Are you shitting me? I mean honestly it completely changes how Elronds Council should have gone in the Fellowship. Not to mention that Gandalf would have NEVER survived a fight with Sauron. The Silmarillion was quite clear on this. Radagast the brown. I call him Jar Jar for a reason. They took what was a really interesting Maiar character, and turned him into this absolutely retarded character that has a sled pulled by rabbits. I get they did it for the kids, but come the fuck on. The majority of the Dialogue.
This is all I can come up with off the top of my head
I'll grant you that visually the movie is impressive, but thats it.
I can name another movie that was visually really impressive for its day, but it fell flat on telling a story and was nowhere near the source material, that movie is "Starship Troopers"