Looks nice, but it still leaves me with the same feeling as most other tools like this: any co-located team is better off with just whiteboards, cards and sticky notes.
Plus most of these tools are geared towards the structured initial development phase, and become considerably less usable once a product is live and goes into maintenance mode. This is odd, since the major part of a projects lifespan consists of maintenance, not development.
The one great missing online tool IMO is one that both integrates and separates the way the user experiences issues (like via Zendesk) and the way those issues are split up, prioritized and handled by developers (any known issue tracking system like Redmine etc).
Right now, every team I know either uses two systems in which the relationship is handled manually (and thus labor intensive and prone to errors) or one system that is only geared towards either audience.