As for the game, it's really okay, but then that's surely only a milestone to a more advanced game ? I mean, it lacks tons of features any TD game has, art is minimalistic, towers are (too) completely classic. Some glitches also, for example you don't get sent back to the main menu after losing. But then again, that's a very good basis for an awesome game.
It seems (in unlimited mode) you don't get any gold from kills after level 60, dunno if it's intended to put an end to the unlimited mode, or to make it much harder (you don't get enough gold up to level 60 to build and upgrade 5 ultimate towers :()