I posted about this before. 'tis a fantastic thing, to have the complete Narn finally: patched together from notes which have been part-published in various forms over the years. The other Great Tales were in even less of a complete state; so it's likely this is it, no Tuor and the Fall of Gondolin or Beren and Luthien for us.
I've not read the actual body of the text yet, so I will report back on how that is. It's certainly far more accessible than The Silmarillion.
random geeky tolkien notes: Gil-Galad is not listed in the genealogies, thus neatly side-stepping the problem of whether he was the son of Fingon or Orodreth. and Angband is still not marked on the map.