I just got into this the other day, and I'm really impressed. I have NOT played other CCGs, so I can't comment on the complexity of it. It seems like the learning curve is very fast and simple --- it's just the strategies you come up with that are more complex (or as complex as you want it). I haven't spent any money on packs. I may in the future.. but not a lot. Maybe that $10 set or $20 and have it be a one time only thing. I'm OK with doing dailies and then doing arenas to unlocking more cards and then DE'ing the duplicates and create ones I need.
I have a lot of hope for this game. It's new, so anything goes. Currently, there's a promo that if you win 3 matches you will have the "Hearthsteed Mount" in WoW. I like that a lot. This gives me hope that they will have special events that will lead to other prizes/neat things like that. Perhaps even do stuff in their other games can unlock some decks.
The main thing I am HOPING.. HOPING... for.. is they add vanity pets/mounts/extras to their decks much like TCG. Although I would love if they added the exact pets/mounts/extras to this game, I'm hoping for something new. This doesn't seem unlikely, and if they make these pets/mounts/extras available only (by chance) when you purchase packs, I'd assume that sales would increase a lot. Hell, I know I would set up some kind of limit to allow myself to buy packs.
Regardless, It's a pretty great (addicting) game that has potential to become a lot better and much more involved with their other games. I'm already loving that people who purchased the D3 expansion received 1-3 packs. It's those kinds of extras that, if done right, can make Blizzard even more enjoyable. No, I'm not one of them blizzard fanboys.. I promise.