I picked Mount Hyjal over Vashj'ir simply because I'm a druid. Why wouldn't I want to go hang out where all the other druids are?
It feels like a very linear zone, where the player moves from quest hub to quest hub. While it always makes sense, I feel more boxed in than I did in WotLK. It's possible to explore off the beaten path, but I don't feel encouraged to explore. Instead I have the feeling that if I just follow the quests like a trail of breadcrumbs I'll see everything that there is to see.
It's nice, but takes some of the fun out of the exploration bit.
There is a very nice breadcrumb to the new Blackrock Caverns instance though, complete with mole machine that lets you discover the portal to the new instance without having to trek all the way to Searing Gorge to do it! On the other hand, wasn't the point of having to discover the portals so that people don't get lost trying to find their way back to the graveyard? I honestly wouldn't know how to get to the new BRC outside of the mole machine if I ever died!
Hyjal has a lot of plot and lore though, including ever funny moments that can only be had as a moonkin druid. (And if you're afraid of spoilers in the first half of Hyjal, you may want to stop reading here.)
Ferals get forced out of their forms to avoid such silliness as cats riding horses and other such nonsense when a quest calls for mounting up or riding vehicles. But moonkin? Nah...
It's perfectly natural for a moonkin to be riding a giant wolf, right?
But the best part of my night was yet to come. As part of a hero's duty, one of the quests in the first part of Hyjal is to take command of the Eye of Twilight, which gives orders to some rather dim-witted Twilight Cultists. Through a series of events, your character does exactly that, and you're treated to a very nice graphic of your character hovering above the eye and giving instructions to those obedient peons.
Even if... you are currently a moonkin...
I did mention those cultists are dim-witted, right?
I'm hoping the storyline gets more interesting later on. I know it's kind of odd to think about story in an MMO, but I feel like Hyjal is swimming in so much lore that it could benefit from a little more structure, and not the quest design kind. WotLK had some nice moments where a very personal story was told among all the lore, and I haven't found that yet.
The Ancient Lo'Gosh came back into the world through my efforts, but I didn't feel like "All right! I did something really cool!" Replace him with a minor wolf spirit and the quest chain could have been done in Ashenvale.
Epic characters call for a epic quest with an epic story.