I do enjoy defense games...
This one was a little blah..
However the good things I will list, and many newgrounds users contribute to as well
1.) I did enjoy the different enemies - it kept the game from becoming bland. The different enemies made the game player have to switch up their strategies, be it from spray an pray, to a more accurate approach
2.) The differentiating weapons were also a pleasant surprise, and allowed for various players to take grasp of a variety of strategies, whether it be spray and pray style, to overloading the screen with scolding plasma.
3.) An effective use of flashkit sounds - The sounds and effects were used efficiently.
4.) This being an early submission of yours, it is well done.
Suggestions---
The game itself did seem to have a variety of glitches, including an annoying on where the enemies could hide on the sides of the screens so that they would remain well hidden.
Maybe post a link to the sequels you have made, or perhaps other games? I can see you may have a future in flash, and I would love to follow your progress.