I love dragons. Who doesn't love dragons, especially when these are scaling dragons? The original iteration of Twilight Drake was that it was a 4/4 and the Battlecry effect granted it +1/+1 for each card in your hand. Getting these out on turn 3 (as the second player with The Coin) was immensely satisfying and it forced your opponent to respond immediately or start taking huge chunks of damage. The new version of the Drake has it starting out with a static 4 attack but the health scales with your hand size. This makes it extremely durable in the early game and still somewhat useful in the late game. Prior to the patch, I'd have 7/7 Drakes early on but once I reached the late game where I didn't have as many cards in my hand, it turned into a 3/3 or a 2/2, rendering it almost useless. Now, at least it will still pack a punch with the 4 attack!
Playing the Twilight Drake
You have a slight edge if you go second due to The Coin. You can use it on turn 3 to bring your drake out early, or wait until turn 4 and it'll act as an extra health point. In most cases, your drake will end up being a 4/5 or higher. The Twilight Drake's potency will be impacted by the type of deck you're using, too. Playing Twilight Drake in a heavy minion deck is almost a bad idea because your hand size will often be low as you're playing minions to overwhelm your opponent. Ideally, you want to play these in a more control-based deck like Mages and Shaman where you'll find yourself holding onto cards and reacting to your opponent's moves.
Playing against the Twilight Drake
While it is possible to go toe to toe against the drake in combat, it usually is a better idea to eliminate it with a crowd control spell. A Polymorph or a Hex will immediately neutralize it. Silence effects will remove the Battlecry and drop the health back down to 1 allowing you to send a weak minion to get rid of it. Also, while the drake will have a large pool of health, it doesn't have taunt. You can send your minions after it, but you might end up in a situation where the Drake takes down two or three of your minions before it dies. Shaman decks can easily deal with this by simply using Earth Shock. Read the wording of the card carefully: Earth Shock silences first, then deals 1 damage. So the Twilight Drake loses the health bonus from the Battlecry and then succumbs to the 1 point of damage.
All in all, a handy card to have for control users. It plays strongly with my Shaman control deck.