Where's the burndown chart (or any task effort estimates at all)? Where do I maintain my product backlog? This tool feels more suited to something like XP or generic Agile than pure Scrum to me.

But that's the problem with project management tools: everyone's got a different mental model for organizing work and measuring output because nobody strictly follows all the practices of any one methodology to the letter ("Agile is empirical," after all). You adopt the practices that work for you and your team, which means you have to create your own project management tools adapted to that unique workflow (unless you're lucky enough to find the tools that someone else created meet your needs perfectly).

Otherwise, you're forced to adapt your workflow to the tools you choose.