I think it's good that they simplified HS a bit. I don't think it would be very popular if the mechanics were as complex as the big ccg/tcg's like MTG. There's MTGO already for people who want an extensive card game experience, and it will be hard to get TCG players to switch to hearthstone.
With simplified mechanics, however, they will attract a wider audience. Will it last long? I think so. It's easy to implement a game like this on Ipad, Iphone, Android, w/e. And I can see myself dueling it out while I'm in the bathroom.
That said, the Digital card game market is pretty saturated atm with games like MTGO, Solforge, etc. but the game looks very polished and fun. I think it's here to stay.