A fun game that's worth giving a try. They don't let you trade your cards though, and the prices of packs are really high. You also get far fewer rare cards with packs you buy with coins earned through play. All of this makes it quite hard to make a specific deck you want without spending well in excess of 100$ Putting the barrier to entry very very high.
I will also never understand why this and other f2p games don't just let you keep playing them. I spend more when I play more, but I never pay to keep playing. Maybe most people are different.