Some feedback:
For a little while I was confused about the upgrade tree because I couldn't get something adjacent so I thought I had to follow a linear path.
It wasn't immediately clear that towers had to be on your territory to function, that was also confusing for a bit.
Before you can draft towers, your runs are vastly better if you get lucky and only get a few types of towers so you can merge them and get more. I'm not sure what a solution is.
A downside of leaving behind towers is that it's harder to get the loot from the enemies they kill.
The "wishlist" message after every section makes it seem like that's the end of the demo which could confuse some people.
The overall experience feels very solid though!