I dunno, man, some reviews say the microtransaction stuff is easy to skip. And I've done all sorts of stupid grinding over the years for a "true ending." Hell, sometimes a true ending was just a different picture at the end. Luckily, playing Mordor was so much fun that I have no problem playing more.
My understanding is that you can do everything without spending more money. If I can get 50 hours out of fun for $60 (minus Prime savings), then that's a heck of a worthwhile purchase to me.