Oooh, the almighty books. I have read it, it is some really heavy reading stuff, but a great world. I would recommend reading LOTR, before reading "The hobbit", its a breeze if thats done first. But movies and books usually have changes, because of directors portrayal, while in books you can kinda imagine it yourself. But i did notice changes from book to movie, for example:

Frodo was more portrayed braver in "Fellowship of the Ring" and the movies made it more right on the books on his character in "Two Towers" and "Return of the king"
For example:
In the movie, Frodo dropped the sword when he saw the nazguls on weathertop, while in the book he showed courage by fighting them before he got stuck.
Also: In the movie an female elf comes to escort frodo to safety.
In the book, a male elf Glorfindel met Aragorn and let Frodo use his horse, when the nazguls came he rode himself, and the river was due to Gandalf and Elrond who could control it from where they where.

I could go on about many changes from book to movie, but in the end, it still potrays the main story ok. Even if they switch what role some play. The same can be said about The hobbit movie aswell. I personally think its ok movie, and the book is old now, but is still a classic for anybody to read.

I say, entertainment is entertainment. It does stay true to the story, so thats all i need. Aslong as it is fun, then i consider that pretty good.