I grew up, as you did, with Tolkien's Hobbit. I read it several times, fell in love, moved on to the trilogy and eventually The Silmarillion. It was part of growing up, and a fine part. I married a Tolkien fanatic, and we made sure our offspring imbibed the books as we had.
I, however, sat through his Hobbit movie listening to my husband, a Tolkien scholar of sorts and a Tolkien purist certainly, groaning and grumbling and swearing he'd not come to any more Peter Jackson movies.
So, without further ado, I plan to make a list of significant departures from the book, that Mr. Jackson chose to make. I do not judge his motives; I'm sure he had astounding limitations and priorities and restrictions that produced these departures. Still, departures they are, and each one chips away a piece of Tolkien's world as we all know it.
1. Bilbo loves visitors. He has many pegs in his hall, because he loves for people to come by. Somehow, Peter Jackson (hereafter called PJ) depicts him as a curmudgeonly hermit who does not want any company.
2. Bilbo's hobbit hole is designed as a single tunnel with rooms off of that tunnel, not a prairie dog maze.
3. Hobbits wear bright colors, green and yellow particularly, and their feet are covered with curly brown hair. Perhaps that would have been too cheerful and whimsical for PJ's movie?
4. Bilbo's pipe is massive, even by human standards, and reaches nearly to his feet.
5. Gandalf's hat is blue.
6. Thorin is an old dwarf, and he comes with Bombur, Bifur, and Bofur. He is not youngish and sullen. He initially praises Bilbo as "a most excellent and audacious hobbit," blesses him and exalts his wine and ale. Gloin is the one who doubts Bilbo in chapter 1.
7. Bilbo is more complex in chapter 1 than PJ allows. His Tookish heart is stirred and won over to the idea of an adventure, and he's excited to go, during the night of song and planning. PJ depicts him as altogether alarmed and unwilling to go. This is simplistic, inaccurate, and sets Bilbo's character for the viewer from the beginning.
8. The music. Granted, PJ did try, and I enjoyed the one dwarf song. But there was lots of music in chapter 1; it sets a tone of beauty and mystery, and lends great complexity to the dwarves' character. And the dwarves have carried their instruments with them -- cellos and a harp, a drum and clarinets. The music weaves a magical web in Bilbo's home and his imagination, and helps woo him to the task at hand.
9. Azog is a goblin, not an orc. This depiction of him as a massive orc, much like the ones Saruman bred at Orthanc, is ludicrous. As a goblin, he could not have fought during daylight.
10. Thorin's father went insane in the dungeon of the Necromancer. Why PJ decided to include so much of Radagast and Dol Guldur, the Necromancer and his acts, and failed to mention this one important link involving Thorin, I cannot guess.
This is chapter 1, as I go back now and read again Tolkien's The Hobbit. I enjoyed many parts of the movie, particularly Martin Freeman's rendering of Bilbo, in spite of PJ's failings on that score. The music was sublime, and I wanted more of it. I wanted more magic and less violence. I wanted more musing and less mayhem. I wanted Tolkien's story for a 10 year old, instead of a modern movie for a 25 year old whose appetite tends toward decapitation and terror. Still, there are wisps of Middle Earth in the movie, and for that I'm thankful.