I had read LOTR just before the movies came out and I think Jackson did a pretty good job, although the books have a different feel with all the walking bits and the songs etc.

I agree 100% about The Hobbit though, the movie was pretty decent, but really feels very different to the book. I think this is expected though as they extended a pretty small book to an entire trilogy of films and adapted what is essentially a children's story for a far wider audience.