I recently went to see The Lord of the Rings: The War of the Rohirrim in the theater. The reviews have been all over the place about it, and I think it has struggled because it is often seen as the test case for whether the 'franchise' can survive the general disaster that was The Rings of Power. This is unfortunate; it demands of the movie something that it probably could not have delivered anyway and I think that while it has a number of flaws, it mostly succeeds at what it was actually trying to do.
(1) In practice, everything Hollywood does with ideas from The Lord of the Rings is make prequels for Peter Jackson's The Lord of the Rings movies. Rings of Power, for instance, is clearly at times trying to be an unofficial prequel; the Hobbit movies were more LOTR movie prequels than they were adaptations of The Hobbit. War is not an exception to this tendency. On this front, however, it does very well. It is, without any doubt whatsoever, better as a prequel to the LOTR movies than Rings of Power is. It is also better as a prequel than the Hobbit movies, with the caveat that the highs of the Hobbit movies (usually when the movies bother to adapt the book directly) are higher highs than War manages to achieve.
(2) At times the animation is excellent, but at times it seems stiff, clumsy, and choppy. This is emblematic of the movie as a whole; it does some things very, very well, and then it will suddenly have a rough patch in which the story, or the character motivations, or the ideas seem clumsily put together.
(3) Helm Hammerhand, voiced by Bryan Cox, who seems really to commit to the larger-than-life aspect of his character, is almost on his own a reason to watch the movie. Literally every time he is on the screen, the story suddenly becomes more interesting. He is also the character who gives one the most sense of well-roundedness; the movie really sells the idea that this is an extraordinary man and exceptional king who is dealing with a new situation he does not fully know how to handle.
(4) The script sometimes has a made-by-committee feel, which is probably due to an inability to work out the complications of having had two different writing teams as well as considerable input from the director. This means that sometimes even very good ideas are not adequately developed. One good idea that I think could have been done better is the focus on Eowyn, who narrates the story. This is not made adequately clear in the story -- if you don't recognize Miranda Otto's voice, nothing would alert you to the fact until the credits. This is an idea that could have done much to bind the story together; it explains the focus on Hera rather than Helm; and it would appeal to members of the audience who would like what is effectively an Eowyn story that does not damage Eowyn's canonical story. Eowyn telling a tale of a heroine who inspired her is something that could have worked exceptionally well, if there had been more commitment to it and more emphasis on it in both marketing and narration.
(5) The main character is Hera, Helm's daughter (mentioned in a sentence but never named by Tolkien). She sometimes gets sharply criticized in reviews, but I actually liked Hera as a character, for the most part. She actually makes a very plausible princess, for the most part, which is increasingly uncommon on the screen, The primary difficulty is that we don't get a full sense of her motivations.
(6) Character motivations, in fact, seems to be one of the things with which this movie struggles. The strongest character usually aren't given any obvious motivations for their major actions. The weakest character -- Wulf, the antagonist, is the most obvious one -- have motivations that make remarkably little sense, and it gets irritating at how much of the plot is moved forward by Wulf repeatedly doing exactly the opposite of what General Targg's consistently accurate analysis of the situation indicates he should do. There are also broader motivations that are somewhat baffling. Rohan and Gondor seemed to be assumed to be entirely separate kingdoms, when in reality Rohan is effectively a vassal state, the Rohirrim having received Rohan as a grant from Gondor when they as a tribe allied themselves with Gondor against other tribes, and having received the grant on the condition that they guard Gondor's northern border and provide military assistance in friendship. Thus it makes no sense for any Rohirrim, however interested, to protest the king's daugther marrying a Gondorian prince, as if that were itself a problem. The relation of the Rohirrim to the Dunlendings is never made sufficiently clear for the particular story being told, either. In the books, the Dunlendings are separate tribes who are effectively kept under close watch by Rohirrim, and serve as one of the examples of how the Rohirrim's tendency to mistreat other tribes nearly results in disaster in the War of the Ring. In the movie, it is much less clear how the situation is being conceived.
(7) This is movie that does not shy away from the dark and the violent; it is the most gory of the big-screen presentations of Middle Earth. It generally handles this well, but audiences should know it beforehand.
(8) One of the weaknesses of the movie as a prequel to the LOTR movies is that it sometimes tries to shoehorn in allusions, either visual or narrative; only a few of these allusions work well at all, and a couple of them end up being cheesy. Others that most work well -- like the brief introduction of Saruman -- could have been set up better, and thus despite being nice additions end up feeling tacked on.
My overall recommendation is that it is worth seeing; it is mostly better than anything since the LOTR movies. It has definite flaws, and sometimes feels like it needed one more serious revision or editing run-through, but it mostly does well what it is actually trying to do, and I think it holds up well in comparison with a lot of what is on the screen these days.