I finally secured an invitation to the beta for Blizzard’s new game, Hearthstone. I’ve played Magic: the Gathering for many years, so I’m very familiar with how collectible card games work, and they’ve done a great job at bringing the format to the screen. Probably a much better job than Wizards has done with Magic Online. It plays fast and is very easy to learn, with all of the concepts taken directly from World of Warcraft.
There is no trading or selling of cards in this game, so you won’t see the gold farmers migrating in to make cash from this one. It also reduces the chance of people only buying the best cards in the game to use against you. You’ll still be at a disadvantage to people who have spent cash, but players won’t be buying packs only to flip them for cash. One aspect I do like is the ability to disenchant cards you don’t want, turning them into dust, which you can then use to create cards you specifically do. 
You can play for free, but you also have the option to buy packs and arena tickets with real money. You don’t need to buy them, but collecting them from currency won in the game itself will be painfully slow, and you will be facing opponents who have much better decks than you do.
It seems fairly fun, and to drop in and just play a few hands at any time will be nice. I just don’t know how much long term enjoyment there will be, as some of the more complex mechanics from Magic are not there, so it may get somewhat repetitive after a while. It’s free, so there’s no reason not to jump in, at least for a while and try it out. The Battlenet friends list is fully integrated, so you can play against your friends easily enough.
I’m also playing Magic 2014 on my tablet, which is mainly a single-player experience, but it really offers some great game-play.