I never realised how much I sucked at TDs...
This game is fantastically made. For me it is extremely challenging (I can't even get past level 1! I suck...), yet fun and addictive enough for me to not ragequit. Which I admittedly have a habit of doing quite a lot...
It has good art, is consistently entertaining, the gameplay, however lacking in originality (tower defence games all share the same base traits), has enough of its own charm to make it unique and set itself apart from the rest of the games in its genre.
Good job! I'm looking forward to seeing more games from you!