Good game, but the difficulty was too much for me.
I liked it but it was much too difficult to get enough money for anything useful. The crossbow costs the same as 25 health, but 25 health isn't even enough. 3000 dollars and I can't even fully repair the basic castle? Not even worth it. I tried one reviewers suggestion of using the first weapon, the sling shot for the first 8 waves and support, but I didn't even get enough money to buy a support unit til the 7th wave, and by then it was too late.