Its good
I liked it, I'm a fan of tower defense. Needs a lot of work. As said below the speed increase makes towers do almost nothing. Your biggest problem is that the towers are like mortars, they don't directly damage the enemy but more so of a hit an area damage. I noticed that when ever a enemy got to far away even though my tower was shooting at it it wasnt getting hit. the towers are boring they all do the same thing just different colors plus any tower can become the same by upgrades. How about some effects like slow or splash. I did like the graphics. music was getting annoying. The lack of enemy designs was boring, same for model of towers. If your going to make it endless you need something more to draw in players to stay awhile and keep playing.