Well, after actually playing a lot against other players, I must admit that I'm sold. This game is truly addictive!
It's going to be a challenge to create a good defence deck. At this point I'm playing a mage deck, but with little succes as I've only won one game so far. My games do take about 20 rounds or so to finish at average but I do notice that I rarely have a chance of winning. I'll need to rethink my deck and not just blindly add all possible cards to boost my numbers.
It is hard however to think of a strategy with so few cards of one type available. Trading might help, but that's still a bit buggy at this point. And the drop rate of new booster decks is pretty rough, understandable but regrettable nonetheless. Not everyone will be willing to spend about 50USD before being able to create a good deck that might withstand other players. The starter decks should not be used to play against others much, just not good enough.
Anyway, this game is a serious threat to my online activities, to say the least!