First off, I want to say this is a good film. Not the best of 2001, but good nevertheless. Lord of the Rings will justly be remembered as a clasic of cinema, not just because its entertaining, but also because its vast and long. Hollywood likes epics, and LOTR is one.
Right - so there is nothing outstandingly wrong with the film. Acting is good, cinematography is good, direction is good. Its weekest point is the script, you see Tolkien wrote an outstandingly creative book where a world was described to the reader as the story passed through it - the story was a means of describing the world. With films, that sort of thing doesn't work quite as well. Also, much of what was outstanding about the world Tolkein described is now cliched in fantasy books. So while the world is still there (and oddly intrudes where it is neccessary for the story) it now takes a back seat and is left as stunning visuals. And that leaves a perfectly reasonable, but not overly special, story holding everything together
The good side for this is that things which are neccesary for the world but not the story vanish (no Tom Bombadil - woohoo!). The film is able to move quickly and even dwell on action sequences (which are all impressive). The pace is fast and well controlled. Nevertheless, none of this is what made Lord of the Rings, Lord of the Rings. What we have is an epic, important fantasy film where production values support a slightly week storyline. I'm not complaining I'm more than happy to have spent 3 hours of my life watching it again, and would do so again were it not for the pains in my leg I had to endure for the last hour and a half.
All told, I'll hand it four and a half hairy feet out of a possible five. Its a better film than you're likely to see, and it will be remembered long after higher rated films are forgotten, nevertheless, it just isn't quite as good.