When I think of the new animated movie “The Lord of the Rings: The War of the Rohirrim,” I think of the words of the legendary public speaker Bilbo Baggins, who probably would have described it like this: “I like half of it half as well as I should like, and I like less than half of it half as well as it deserves.”

Mr. Baggins was a harsh critic, but he knew how to turn a phrase. His famous quote from “The Fellowship of the Ring” cleverly articulates that something isn’t very good while simultaneously allowing that some of it may be okay, and you’re just too annoyed to care. “The Lord of the Rings: The War of the Rohirrim” is an underwhelming production with hit-and-miss animation (mostly miss) and largely generic performances, and yet it’s not a complete washout.

“The War of the Rohirrim” is...