I'm wondering if (or how much of) it's based on material from The Silmarillion. I've always thought someone ought to try to make a coherent story out of all that history and lore, but what a task.
From the rundown they did of cast and characters the other day, it seemed like several of the characters are completely original and that others that aren't are being adapted in ways that there's no lore basis for (Galadriel being a military commander). My hopes are not high. Tolkien left a wealth of material not just in his books but also in his appendices and letters. There's no real reason to be making stuff up for this. Especially when the glut of TV shows being produced has led to some very mediocre (or worse) writers rooms the last few years as the real talent gets spread increasingly thin.