I do use it as a project management system (as a freelancer), but my main use is having it as my brain dump. And I love it.

I have my knowledge base where I put notes of courses I take, interesting programming links or business insights I see in the wild. It's also perfect for writing down ideas and organizing small projects.

Standard to-dos never clicked for me. I usually assign a time slot for the task in my calendar or have it listed in the project page.