It's interesting how my playstyle has changed ever since I got my flying mount. I'm still questing in Shadowmoon Valley, but how I approach my quests has greatly changed.
Before, I used to run to the quest area, fight my way to the quest target, kill them or recover the item, and fight my way back out. As a paladin, you really don't have any tricks to avoid any of this. It's a very straightforward process.
Now with a flying mount, it's very different.
Step 1: Aerial Recon - Scout out the location and find the quest mob.
Step 2: Paradrop in - Hover directly above the quest mob and dismount so you fall to the ground right there.
Step 3: Kill the target, get the quest item.
Step 4: Jump out - mount up and take off.
Very commando-style gameplay. It's interesting because there are a lot of design implications for this playstyle. For example, I'm probably going to miss any quests that start between the base and my target. I'm just not going to see them.
I'm also going to kill a lot less mobs. Before you could count on having to kill many mobs while getting to the target, and that has implications on how much gold and xp I will get (or would have gotten if I was still levelling).
I mean, it's not a "bad" playstyle. A lot of the fun factor in having a flying mount comes from being able to do things like this. And I think Blizzard realizes this. There's a couple of quests in Shadowmoon Valley that seem specifically designed for this playstyle (Setting Up The Bomb, in particular).
But at the same time, I think it has a lot of future implications for how Blizzard is going to design expansions. Blizzard is, in a lot of ways, masters of "directed" gameplay. You get a quest to go to X, and on your way you get a quest to go to Y, and Blizzard carefully leads you around the world, allowing you to experience everything. I think we're going to see fewer quest NPCs wandering the roads of the world, and more quests at the various quest hubs.