^ I agree that reproducing the original narrative would probably not have worked where the army of the dead is concerned. It's a case where the movie had to simplify one way or another. Nonetheless, the final result leaves much to be desired.
Gollumn tells Frodo and Sam that when he was tortured by Sauron he saw four fingers on his black hand. Ergo, vis a vis, concurrently, Sauron had a physical body.
I do recall that line, which is probably the strongest suggestion of Sauron having a physical form of some kind, but, where Gollum and the ring are concerned, there are many other possibilities. We see on multiple occasions that lust for the ring tends to warp characters' perceptions of reality, so it's possible that what Gollum saw or thought he saw was like a shadow of Sauron's original form. Example: the Nazgul do not have physical bodies, but they sometimes appear to be humanoid, especially to Frodo when he is wearing the ring (he sees like a spectral version of the ringwraiths' original physical form).
Characters closely associated with the Rings of Power tend to see each other differently than other characters, and have the ability to perceive others as they exist in the "spirit-realm," etc.
I'd rather see them as humans, with their flaws and shortcomings, which is exactly what Denethor is in the movie.
Denethor is a tragic figure, which includes deep flaws but also strong admirable qualities (both are necessary to achieve any sort of tragic effect). In the film he is completely corrupt and contemptible, so all sense of grandeur and tragedy is lost.
Similarly, portraying Gondor itself as pathetic and helpless detracts from the epic quality of the attack on Minas Tirith. The drama comes from the fact that this impregnable fortress that has stood for so long against a mighty foe is FINALLY, after decades of planning and centuries of conflict, against overwhelming forces marshaled from near and far, etc., etc., for the first time being breached by an enemy. Basically, you need to build up whatever you are going to tear down for that process to feel significant.
This is what Tolkien does expertly, and that is why the narrative is so influential and so compelling, both as world-building and pure storytelling. By comparison, the film version of the RotK is rather amateurish. Denethor is a good example of that.
What struck me most when I saw RotK in the theater was how often the climactic sequences were laughter-inducing, rather than tense or exciting. Basically, at a certain point in the middle of the third film, Jackson loses control of the narrative and it starts to produce the opposite of the desired effect.
While the cuts to the Ents can be jarring, and one can quibble with some of the details, the same thing doesn't happen in the climax of the second film, which is supposed to be exciting, and is.
