I won! It was fun :)
My main 'do not like': The auto-select nearest upgrade. I'm used to being able to use left click to drag around. So there was a lot of "Oops! I wanted to look over here but instead I upgraded... uh, something?"
More general: It uses this upgrade map/system that EVERY game seems to have nowadays. So I wouldn't gripe specifically at this game for that. But Request to All Devs: Please stop using that. It's a generally bad upgrade system. It very rarely makes sense for a given game. Players - ME anyway - don't like having to upgrade stuff they're not interested in, just to get to what they want. Or worse, just to find out if there's something they need.