Good Game/Bad Cash
I thought overall this was a good game. Weapons did decent damage, etc. Enemies were properly leveled up as the levels went by. The pause button is probably my favorite feature that is lacked in every other Defense game I played.
The only thing I didn't like was the cash flow. Getting paid one dollar an enemy killed is kind of cheap. With the least expensive thing being 30 dollars, and everything else being in 100+ dollars, and the Finance Center upgrading with such a high price compared to what you earn per kill. Because of this lack of funds, I couldn't get past the 20's. If you upgraded it, like say 5 dollars per kill, and after X amount of levels(Keep it a small number) you get a little more per kill, that would make the game better.