Don't know if anyone already said this but if you dont mind waiting, the health and mana regen equipment still have an effect even if you arnt in battle. So make sure to take advantage of it rather than wasting gold on pots.
The game itself is solid but the starter decks need some more range or better start spells, I started with the demon worshiper deck and now that all the enemies can spam archers I cant make it past the halfway point even if i summon more than 50 units. I'm sure that once I get some ranged cards or some spell cards it wont be so bad but given thats up to the luck of the draw I might have to frag this save file just to make progress which is a pretty broken situation.
There should probably be different control modes, it tends to fight the keyboard controls if the mouse picks up a twitch. Also a keyboard fire button would be a major help, the autofire is nice but I like being able to time my shots. Otherwise the game is sound with a pretty decent assortment of upgrades.