Really polished app. Been using it for a few months now, and with the latest version (1.62), it kind of does everything you'd need as a freelancer.
Automatically adding activities to projects based on rules (like the title or the path of the open document), but also being able to manually add them is a bliss. I'd say being able to manually create an activity that wasn't tracked would be the only thing missing here (think of phone calls, for example).
The app also offers pretty solid invoice creation and management, with really great nice to haves, like automatically pre-filling the hourly rate & contact info based on the current project's previous invoices, or keeping track of what was invoiced so far and not allowing you to add the same activity to more than one invoice
It also caters to the non-professionals, with simple to categorize activities, and a beautiful Dashboard, where you can see at a glance the productive & distracting times (also as percentages), and a per-hour/day/etc graph for the currently selected period.
Great developer as well, open to feedback and suggestions!