CCGs have always appealed to me but there was always something I didn't like about each game. In Magic the Gathering, it was too expensive. I got tired of always getting killed by the rich kids and mana flooding/drought was always a problem. Shadow era (basically a MTG want-to-be) was a good alternative but hated how my creatures never returned damage unless they survived the attack from an enemy creature. Made it too difficult to change the momentum of the game.
But Blizzard has perfected the CCG. Hearthstone is the new king of CCGs. This game is truly free to play. Basically the WOW trading card game that only achieved semi-popular status (cant say for sure never got into the WOW CCG). I have purchased dozens of card packs without ever spending a dime. A feature they left out (for the better!!) is the ability to purchase specific cards, this prevents the rich kids from stacking their decks with legendary creatures. People who spend money will still have an advantage because they have a variety of cards, and probably more legendaries too, but it prevents easy domination by money. Also mana is no longer handled with cards, every turn each player gets 1 more mana, so both players are on a level playing field. Everything is fairly well balanced, and there are a wide variety of strategies available. Presentation is also top notch.
There are a couple of features missing from hearthstone, but nothing that cant be easily added in future updates. First off, there is no chat feature. Just preset emotes. This really hurts the game because a more relaxed and social environment is one of the biggest appeals of online CCGs to me. Versus when you play battlefield people arent very social because they are busy blowing things up. It makes it very difficult to make friends in the game, so this needs to be changed ASAP. Also there is no tournament mode. Instead we have an arena mode. Which is basically a draft deck mode. You select random cards, and play against others in the arena for up to 12 wins or 3 losses, whichever is first. Based upon how many wins you have when you hit 3 losses you get more prizes (and it does cost gold or money to enter). You can stop playing and come back to the arena whenever you want. Arena is a great addition, but it would still be nice to take my awesome mage deck into a tournament to compete. Also there is no trade option, while not necessary it would be a lot of fun.
All in all, if CCGs appeal to you to any degree Hearthstone is a must. You wont be disappointed