It was sad but understandable that they had to cut out Tom Bombadil, and that they couldn't fit in the complete original ending with the Scouring of the Shire; but at least they didn't send Frodo and Sam into fucking Gondor for no reason. The visuals looked great, although they did increase the violence and gore levels of the fights. There was only one time where I thought that this crossed the into truly gratuitous and detrimental, though. I'd also like to point out that I haven't seen this many flopping blue penises since that unfortunate Smurf Porn incident.
I had heard several times that you-know-what had been removed from the ending, without ever hearing what they replaced it with. I should have known; but I still figured it out faster than Dreiberg and Rorshach. Overall, it was enjoyable (especially in IMAX) if flawed; with the overall sense sometimes (especially the opening montage) that what we were watching was the Cliff Notes version of the Watchmen. Still, it was a decent job for an "unfilmable story". I realize that many people will be outraged by the cuts, changes, and other liberties; but they probably also have a bigger emotional investment in the original than I do.
EDIT: There be spoilers in the comments.