Game controls suck. No tutorializing and it took me 3 games before i even realized how to move the charactr. Speed is too fast for how narrow the passages are in the starter area
I think wave compression research costs just a bit too much. Spending an hour in easy mode hitting wave 30k is a bit rough when i want to both maximize my orange resources and not waste hours of my life doing it
One thing i think the game has a problem with is that if you're using auto prestige on small floor change, most of the armory upgrades are worthless. Only the ones linked to clearing a stage as fast as possible really help move things along