I've been using Tracker since they released a private beta right after Railsconf last June ... it is a truly excellent tool. Tracker codifies the Agile process (more or less following XP principles) way better than any other PM tool I've ever seen.
The tool itself won't make your team more or less productive, though. You really have to understand and be committed to Agile/XP theories, processes and practices for it to work. Tracker can help guide you in that direction ... but like almost any tool, there is a "best" way to use it to get the full benefit.
The tool itself won't make your team more or less productive, though. You really have to understand and be committed to Agile/XP theories, processes and practices for it to work. Tracker can help guide you in that direction ... but like almost any tool, there is a "best" way to use it to get the full benefit.