I played some more and having a total blast. 
I'll admit that much of it has to do with the game being new, and just being amazed at seeing stuff I never saw before, either cards I never saw or strategy I never expected. I'll say again personally, this has the feel of hearthstone in term of pacing, but with more complexity like Magic.
One thing I notice so far(small sample) is that early games rarely get out of control, I think the way the draw system, the passive mana, and the 3 extra "spell mana" you can bank if you don't use all your mana keeps the early game very interesting. On the other, the mid/late game when heroes level, and the big cards come out can see some spectacular turns, and reversals. My last game I had 1 health left, and opponent had 20 and I won 2 turns later taking him to negative 32 I think, so I did like 52 damage in 2 turns. 
One tiny detail I like a lot, when you cannot do anything on your turn, the computer automatically passes, so you can't use the 30 seconds to think about the next turn, it keeps the game flowing at a quick pace.