I've made it known that I'm not a fan of the new double-faced cards. It's not that they don't have the traditional Magic back. No, if they'd just redesigned the back of the card or altered it in any way, I'd be severly pissed. But that's not my issue.
It's the physical logistics of playing with such cards that turns me off. I play with sleeves - ALWAYS. Even my draft decks and sealed decks get sleeves. Playing DFC's with sleeves seems like a huge pain in the ass. If you use the actual DFC in a sleeve, if and when you "transform" it, you have to physically remove the card from the sleeve, flip it over, and re-sleeve it. This will increase wear and tear on the card AND the sleeve.
My buddy Chad has the best solution I've heard so far: He bought some clear dragonshield sleeves. He'll use the proxy checklist card provided in the Innistrad boosters to represent the DFC in his deck, but he'll have the DFC sleeved in a clear-backed sleeve so that when he plays the checklist he can just set the DFC on top of it, and then if he meets the transform conditions, he just flips the card over. That way he doesn't have to de-sleeve and re-sleeve constantly.
It's a pretty good workaround and I hope it works well enough for him to enjoy playing Werewolves - he's been waiting a long time for WotC to make Werewolves a viable tribe, so I hope the tribe winds up being fun for him.
The transform mechanic just doesn't seem fun to me. Some of the cards are cool, but flipping them over is just not appealing to me. That said, there are a few cards I'm willing to put a little effort into accepting the DFC mechanic in order to play.
Let's just go down the list, shall we?
Cloistered Youth/Unholy Fiend
This one is pretty cool, flavor-wise. It's the old innocent-looking-girl-is-really-something-evil trope, and this captures the flavor well. I definitely don't see this being even remotely playable in EDH.
Thraben Sentry/Thraben Militia
A 5/4 Trample wouldn't be too terrible in the format, but starting as a 2/2 for 4, it hardly seems worth getting excited over. You might play this if you're running a Soldier tribal deck, but then again you might not.
Civilized Scholar/Homicidal Brute
The classic Dr. Jeckyll and Mr. Hyde trope. Another card where they captured the flavor wonderfully, but made the card nigh-unplayable in the process.
Delver of Secrets/Insectile Abberation
What were they going for here? The Fly? Or is it meant to be a Franz Kafka-esque Metamorphosis reference? Anyway, a 3/2 Flyer for one blue is cool, but in EDH, this won't have any board impact past, say, turn three or so.
Ludevic's Test Subject/Ludevic's Abomination
Well, I can hardly stand here and tell you that a 13/13 with Trample "lacks board presence" without losing all credibility. I definitely think this is playable, but I dislike it for the same reason I dislike the Level Up mechanic in EDH - you sink way too much mana into leveling up your guy only to wind up with nothing when someone finally Wraths or Paths your dude when you're one level away from something awesome happening.
This is much the same. Clever players will wait until you've spent 8 to 10 mana on this, then kill it in response to your last hatchling counter.
Bloodline Keeper/Lord of Lineage
I will play this. I don't care how much of a pain the Transform cards wind up being. This Vampire is friggin' insane. Damn good card. Should be playable in just about any vampire-themed deck, or even in some mono-black decks that just happen to have a few Vampires. This guy brings his own army of vamps with him, so you don't need that many more for him to be potentially good.
Screeching Bat/Stalking Vampire
Simple, elegant design - gets a five-star review on that aspect. Playability is next to nothing. Great in Limited, probably terrible anywhere else.
Hanweir Watchkeep/Bane of Hanweir
Inquisitor Gang/Wildblood Pack
This one is actually pretty good. It's not parasitic to the werewolf tribe, as it pumps all attacking creatures. I can see it being playable. It's not good enough or exciting enough to get me to play it, but I do think it's playable.
Kruin Outlaw/Terror of Kruin Pass
If this card weren't a parastic tribal card, I probably would play it. I like giving all my dudes Doublestrike. I don't see too many decks having enough werewolves to make this good, at least not until the third set comes out.
Reckless Waif/Merciless Predator
Tormented Pariah/Rampaging Werewolf
Daybreak Ranger/Nightfall Predator
That single red mana on the night side of the card severly limits the number of decks this could go in. The fact that it's mediocre also severly hampers its playability.
Garruk Relentless/Garruk, the Veil-Cursed
This is a pretty powerful planeswalker, and I would definitely consider it highly playable overall. It's not so good, though, that there's any specific deck that I would say "you NEED this card" for, but if you just happen to open one in a pack, you would likely be happy to fit this into a deck somewhere.
Grizzled Outcasts/Krallenhorde Wantons
Mayor of Avabruck/Howlpack Alpha
Human lord side is great. I'd love it if it was just that side. I'm less intrested in the Werewolf side, but that's mainly because most of the werewolves suck. Maybe, just maybe, by the end of the block there will be a place for this guy. Not yet.
Uvenwald Mystics/Uvenwald Primordials
5/5 with W: Regenerate is not terrible. Not exciting either, but not strictly crap.