With my Monk halfway through his required 30 world quests and 2/5 through his last round of class campaign champion missions, I've turned my attentions back to my Hunter. Good old Ordenar was actually my secondary Alliance character when I started, until my Death Knight usurped his position.
While he's sometimes been Marksmanship, I'd say that through most of the dwarf's career he's been all about the Beast Mastery. However, while I'm happy to use Titanstrike (I got the secret appearance but don't have the heart to use a bow when I can be using a gun - where's the alternate gun skin for Thas'dorah, Blizzard?! Funny that I abhor guns in real life but when it comes to fantasy RPGs, I love them,) I've honestly found the Beast Mastery rotation a bit lacking - it's much less about the big burst of a powerful Kill Command and now seems to be a constant maintenance of Dire Beasts.
I've been intrigued by Survival's transformation into a melee spec since it was announced - I've always thought that classes that are pure-ranged or pure-melee and have multiple DPS specs should branch out a bit. Giving Hunters a melee spec makes perfect sense, and if we were designing the game from scratch, it seems obvious to me that Rogues ought to have a ranged spec (in fact, in most games Rogues are primarily a ranged class.)
To be clear - Survival is not what you'd call an elegant spec. There are a lot of overlapping ideas that don't really fit together all that well. You have Mongoose Bite, which is of course at the center of the rotation, but doesn't actually depend at all on your primary resource. There are a bunch of different themes - traps and explosives (a bigger theme if you take Dragonfire Grenade, and why wouldn't you?,) various strikes that do cost Focus, and a bleed ability that I think is mainly there because it was there in vanilla.
Still, with Marksmanship and Beast Mastery both having your sort of wait for the more interesting abilities to light up, Survival will never let you get bored (or complacent.)
Admittedly, I've also taken a selection of talents that adds a bunch of buttons to my rotation - Throwing Axes, Snake Hunter, Dragonfire Grenade.
It also probably doesn't hurt having a melee spec in an expansion where for once things seem to really favor melee dps (though given Beast Mastery still has just as much mobility as it always has, you can't really say that they have a disadvantage.)
I'd guess there are two main reasons you're not seeing a lot of Survival Hunters (though I've seen I think three now in dungeon groups - up from one since the last time I talked about this!) The first is that it's a totally new spec. Outlaw might have gotten its new name, but Survival as a spec has been built from the ground up, making it almost as totally new as Havoc and Vengeance (we'll say it's not quite as much given that there are still things like Freezing and Explosive Trap.) While novelty is not always such a burden (see the popularity of Outlaw and of Demon Hunters) I imagine that a lot of Hunters were already pretty comfortable with their specs as they were, and former Survival Hunters will find more familiar (not totally, but more familiar) territory in the other ranged specs.
The other reason is that yes, this spec is more complicated than the other two. Considerably so. But frankly, while I've mostly been very, very in favor of the class changes that came in 7.0, Beast Mastery and to an extent Marksmanship are stripped down a little too much for my tastes. It's not nearly as bad as Warlords-era Arms Warriors (which was basically just "hit Colossus Smash, wait for Rage. Hit Mortal Strike. Wait for Rage,) but I'm feeling pretty inspired to get into the Survival game.
Also, and I don't know if this is purely just weird stat scaling at low levels, but I seem to be doing way, way more dps as Survival than the other specs.