At the moment it's very clear this is an unfinished game. You could think of the following as a list of things to improve if you want to work on it further.
The main problem is there is very little information given to the player. You get to place girls (towers) and you see enemies which have a health bar. You get a lives counter and a money display. That's about it. You don't get any information about how much range your towers have, how much they cost to build/upgrade, how their power changes as you upgrade, have they even been upgraded yet... They also have poor attack animations, which means you can barely tell if they are doing anything. As far as I can tell, there is only one type of tower and one type of enemy, which doesn't lead to interesting gameplay.
Right now there isn't much to praise, but if you make any major updates let me know and I'll play it again!