A big prize is that you can now barter for Second Age legendary items. You do not get to pick what kind, but with a little more than a week’s worth of farming (or a few days plus all the early quests), you can get a random Second Age for your class. Or a low value IXP relic. Or a single rune. You’ll see a Turbine response on one of those threads: he’ll look into it, no promises.
I have some other negative things about Book Seven, like the weakness of the epic book itself, but I’m sleepy and I can grouse another time.