I've been playing a fair amount of Hearthstone lately (less than I'm playing SolForge, for obvious reasons), and while its billed in traditional Blizzard fashion as "easy to play, difficult to master" I've got to say that Blizzard missed the boat of the first half of that statement.
The tutorials in Hearthstone give you a good introduction to the mechanics of actual gameplay, but the mechanics of gameplay are simple enough that it should be straight forward for pretty much anybody. Where Hearthstone currently lacks, is in explaining and teaching the user about deck building. Using the basic pre-made decks is a recipe to lose, whether you are playing against human or CPU opponents.
Also, the early game has too much grinding. You start with only the mage class unlocked. To unlock the other classes you have to beat them in Practice mode against the CPU. By the time you unlock all nine your mage should be level 10 and have its full basic deck. But then all your other classes are at level 1, and have the weakest of decks. So you have to get on that class and slog your way against the CPU to level 10, to unlock its full basic deck.
I suppose this is fine if you know which class you want to play. You can just level that one class and go from there, but if you aren't a CCG veteran, or you want to try different combinations, it isn't even worth judging a class until you have it at level 10. It simply takes too long to get classes to that level.
Once you get a class to level 10, you can start really doing some deck building. There are a lot of resources online for this, I posted some last week, but Blizzard really should have included this in their tutorials. Synergies may not be obvious to people for their given class, and you're really given no instruction at all in-game.
Overall the game is fun, but Blizzard could do a better of getting new players into the game.