Hey Stoarch,
I just randomly came across your post and figured I'd drop in for some feedback. Keep in mind I only played for about 5 minutes as well as watched your youtube video.
The mechanic, to me, doesn't feel like it gives the user much choice of strategy. I felt like I was simply spawning turrets as much as possible until I died, and I didn't feel like I have much control in the situation. I want to feel like I can make different moves to change the outcome, and I felt like I wasn't able to do so (or at least I wasn't able to catch on to what the intended way to win was in the short time I played).
Hopefully that helps in some way. You've clearly put a lot of effort into it, I like the timing of the music and the battle sequences - it just needs an extra something for the player to feel engaged in the strategy.