Newgrounds.com — Everything, By Everyone.

Ok, let's start at the beginning...

The Good
-It's a TD game. Who doesn't like TD?
-Graphics are stylish
-Explosion effects are pretty cool.
-Kinda like the sound effects (but see below)

The Bad...

1st: No tutorial, instructions or in game information on the specific towers. There is some basic data like range and damage but I didn't know until I actually tried the green tower that they act as the "slow down" tower in the game or that the super expensive towers were rapid fire death machines. There's no info on the exact benefits of upgrading the towers either. It's probably not a good idea for someone who is in charge of defending a location to resort to "Trial and Error" to determine what his towers even do. Could use Rate-of-Fire and best target data to so players can make better decisions.

2nd: No music. Sounds aren't bad but I've seen a lot of complaints in the comment section that they were so good. I'm going to assume I'm one for of those rare mutants that likes pew-pew sound effects.

3rd: Soul-Crushing difficulty. I've tried quite a few tactics on the third track on easy, and I have yet to figure out how to successfully defend that one. Since the yellow big boys are the first thing we see on that track (and they were the last ones we saw in the previous track), it doesn't seem possible that an opening budget of 1000 is nearly enough to deal with that.

4th: Tower placement. I ran into a lot of issues trying to place towers where I wanted them. I've ended up having to set the towers in places I didn't want them and where much of their range advantage was wasted. Also, because the tower placement is so finicky, I wasted way too much time trying to place the towers that I barely had enough time to set defenses. In some cases, I still ended up unable to set up defenses in time due to how specific tower placement needed to be to be allowed.

Summery
2.5 out of 5: It's okay but mostly unplayable. I wouldn't recommend it in its current incarnation.

Pretty good job, I like how it's set up and simplified.

Although it needs a "SOUND OFF" button, at least it's worth playing.

As an experiment in learning, this is pretty good. As a game, this fails miserably. The graphics are poor, there's no mute button, there's no explanations for what each tower does or what upgrading them does, there isn't even any explanation for why green towers appear to do no damage. As for the game play? It's no different from a million other TD games.

Not bad, but the sounds are kind of annoying and it is a little bit hard. Pretty decent made overall though.

For a tower defense game its pretty good but where you can place your towers is not very well bordered you may want to rework your code and resubmit