Pivotal Tracker is great for what it's intended for, but it's a very opinionated tool. It's not a good repository for storing a large number of bugs or features

Pivotal Tracker is great for what it's intended for, but it's a very opinionated tool. It's not a good repository for storing a large number of bugs or features, and as such doesn't have fancy features like "X blocks Y". If you have an external system for your features (we just use a google docs roadmap) and immediately triage bugs (will fix next sprint, or won't fix), it works great. Lots of discipline required, though, and it takes some understanding of their specific approach before things start to make sense.