The game is beautiful. Game play was fun at first but the build path gets stale really quick. 
There is no point of upgrading more than 1 card, stacking upgrades to make an infiite deck is way better. I can't beat the last boss without inifinte because there are not enough sustain cards. Most cards require killing a target and not enough minions spawn.
here are a couple of bugs I think was not intended:
Curse cards stay over combat if exhuased with a card
(practice dummys and frog)camp sites can be use unlimed times. with the 0 cost redraw and the 1 mana for 2 energy and 1 draw card with camp tag you can do some infinite stuff