I like that it's simple, yet powerful enough in its featureset to be able to do almost anything you want with an issue tracker or project manager tool! It has all of my favourite things - custom fields, filters/searching capabilities etc., but also some useful extras such as time tracking & reporting functionality which are not always available elsewhere out there when looking at other toolsets e.g. JIRA / Greenhopper. The UI could definitely look better though. There isn't much else really apart from maybe adding more integrations? We've been using this since 2011 so we're quite happy with how far they have come over those years too :) Great product overall if your requirements match what their offering currently does best i.e. issues + projects = problems solving :).