I really like the change, for the first time ever I've actually had a reason to do all the quests in a vanilla wow zone, while at the same time being the correct level for said zone.
Previously I would only be able to do a few quests per zone before they turned grey and I would move on, with the change I get to stay all in one place until I get everything done and I actually see the story of the zone play out in full.
Is it challenging? No not really for a warrior with heirlooms, but its a start.