Pretty good! though there are a lot of factors stopping a five.
First, ui issues. Like the card's text goes over other cards, or the sacrifice room's cards going off screen (add a scroll)
second, and much worse, are the balancing issues. You get rich and pretty much set for the entire game just by frolicking in the starting matches and killing the same things over and over again, which you can then sacrifice for some zappos and just destroy all stages with little to no thinking involved. This is a tower defence game, it gets boring if you're not engaged. For this, I'd make the lower levels only give low tier stuff, while the higher/harder levels are where the gold is at, creating a better reward for the hard stages (as atm you get the same things each stage). Also, I'd even weaken the units or buff the enemies, as at a certain point it just becomes a mindless game of placing down big boys and zappos and archys. It's especially delulu as you can just go from getting your ass handed to you in a level, to handing them theirs in a snap of a finger. Not to say this is a negative, as it can create a feeling of satisfaction, but their has to be a build up to that. I'd say study how pvz handles their enemies and balancing (not 2), as this is kinda similar. Overall though, I do like this game, it just gets held back by some issues rooted within it.