Seen it before.
Nothing too compelling about this game. I like the different types of tower available, adding to the strategy of the game. However the music is kind of lame and repetitive, which is redeemed by a mute button. Graphics don't seem too special or impressive, save for the background which looks pretty awesome. Shame that it's the same on each level. The gameplay is basic tower defence and after a while, gets a little repetitive.
Overall as far as tower defence goes, this one didn't really stand out as anything special in my eyes, but makes for a nice detraction. That's my honest opinion.