To be honest I feel like the effort on this one was nominal, at best; the weapons aren't thought out very well and the creep waves are just ... well, kind of generic.
That being said, I also think too much time and effort were invested in how to make the game as difficult as possible, which also seems counter-intuitive.
Apologies, due to a lack of on screen labels, instructions, and help I didn't realise clicking the wave bar serves as a speed/wave controller. Thanks for that, incidentally.
So the only major issue I really struggle with aside from the lack of an appealing GUI is the fact that to select the guns for purchase or upgrade you have a clickable surface of about 2x2 pixels, which makes it an iffy thing especially if you're in a desperate hurry to upgrade and can't seem to find that magic little tiny dot. :P
I don't know anything about coding games so I am sure that this was not an easy feat, however you did ask for honest feedback, so I'm just trying to deliver, offer constructive criticism and not derogatory comments.
In line with my earlier post, a menu option to pause, resume, restart or exit to the menu could be helpful as well. :)
The game could use the following controls to help make it easier to navigate and interact with - a volume control, a quality control, and possibly a speed control or a send wave now option. Those are all extremely basic controls on a TD game. Hopefully more advanced versions can offer more maps or levels and tower options as well as much better balancing between weapons and costs as well as exponentially correct financial rewards. :) Hope that helps!