Ask HN: Why do you hate (or love!?) your language's package manager?

We're getting ready to design a package manager for Rel, the declarative relational language we're building at RelationalAI (https://relational.ai/). I know that building a package manager is a fraught task, and that people have very strong feelings about their package managers.

Why do you hate yours? What mistakes should we take care to avoid?

Or if you're one of the lucky few blessed with happy package management, what is it you love about yours?