I played for a while some years back and really enjoyed it, but I should add a disclaimer: I've heard some, what appeared to me at least, worrying rants about how new card design was screwing up the balance. So I just want to get out of the way that I cannot comment on that at all since I never got far enough to notice such problems.
Perhaps if I list what made me like Hearthstone back then, then you can contrast/compare that with other card games.
- Obviously you could buy hundreds or thousands of dollars worth of cards and build a killer deck early on. A serious concern for me then was being steamrolled by such overzealous VISA/MASTERCARD players, as well other more senior players who have spent many months building decks. But I was relieved to find that, even though this did occasionally happen, it was a rare. The majority of my losses against other players I attributed to weak tactics or card selections on my part. So my take-away was that Hearthstone's match making system worked very well, at least at the time.
- I thought the monetary system was very fair given that I didn't want to spend any money on cards packs. I only felt compelled to buy the single player 'mini-campaigns' in which you can earn lots of 'campaign'-specific cards (more on those later). But a completely free and sensible way I thought to obtain cards was through arena games. An arena game costs 150 gold and by doing 5 out of 7 daily quests weekly (you can let them accumulate and do 3 daily quests in one sitting if you want) you can easily earn enough gold for two arena entries every week.
What arena is is a series of games against other players until you've lost 3 times total, with rewards given based on your number of wins. The worst you can do (3 losses 0 wins) is a pack of cards and perhaps also a little gold. The bonus with arena games is that you have to create a deck from a pool of cards the arena gives you, so no-one can use their own personal decks. That is, it is a level playing field. And if you do better than 3 losses with 0 wins then you can win additional card packs and gold for extra arena entries.
- Apart from the 2 or so game modes against other players and their decks (ranked matches and such) there are 3 other completely different game modes that I really enjoyed. Arena was one of them as explained above, and the other two are tavern and the bought 'mini-campaigns'-dlcs. The former is a weird mode which changes once a week I think, containing interesting game modes such as cooperative battles with other players against a very strong 'boss-deck'.
But it's the dlc 'mini-campaign' dlcs that I enjoyed the most. These are completely single player and consists of something like 10 boss-decks that you have to defeat at a normal and hard difficulty, by the end of which you will have unlocked something like 20+ cards from the campaign. And these 'bosses' are fiendishly designed with weird abilities that you won't encounter elsewhere, and which requires you to try and design a deck from your available cards specifically to deal with the particular boss and his/her special abilities.
I think I bought about 2 or 3 of these dlcs and found progressing through each to be great fun but also very formidable.
- Unsurprisingly since it's Blizzard, the game is also polished to a shine, has great music and just generally runs very well. The effects feel great and it has a definite warcraft vibe if you like that sort of thing (which I do)
- Lastly, I'm not a veteran card player or anything, but I did notice that the mechanics were on the simpler side of things. Still, I found that the number of things I had to keep track of in a typical match was about as much as I felt I could stomach at the time, especially given the time allowed to make a move. I suppose I would be up to try a more complex card game some day, but at no point did I feel underwhelmed at the simplicity of Hearthstone's mechanics.
Well, except perhaps in the tutorial.
By the way, one other card game I messed around with out of curiousity was Animation Throwdown:
https://www.youtube.com/watch?v=q1y38Yw_Rbo which kind of makes me angry thinking about it. It is an absolutely excellent idea for a card game : combining for example a Fry card (character) and Planet Express ship card (vehicle) yields a much stronger Fry Delivery Boy card (where he is on his bicycle - see? character + vehicle = scene from show with character controlling a vehicle)
But the whole idea is wasted on an absolutely trivial card game where you don't even actually play against other players! Instead you play against the AI using another players deck... Such a waste of an excellent idea :\