Saw The Lord of the Rings last night and have only one word, WOW. The visuals, costumes, sound, etc were all fantastic. They did a great job making a movie that will satisfy the fans, without being over the heads of people who have never read the books.
The time constraints of the movie meant that some stuff had to be cut. The flight from The Shire to Rivendell was very abreivated, as was the time they spent in the Lothlorien. Glorfindel is left completely out in large part to push the Aragorn/Arwen love story line. The only major plot inacuracy that I saw was that Gandalf had already escaped from Sauraman by the time Aragorn and the hobbits reached Weathertop. I also think they put a little "easter egg" in the movie for the biggest fans, I'm seeing it again tonight with a different group of friends and I am going to check for it more closely.
All in all it was a throughly enjoyable movie, and I think a lot of people are going to watch the movie and go out and read the books. If you haven't read the books, watch the movie first, and then read the book, it will be a much more enjoyable experience for you. But in any case go watch it, I am probably going to see it three times in the first week it is out, and it will be worth every penny.