Time tracking features are similar, I believe Wakatime might have a couple of reports more and git commits integration. For now, CoderMirror supports only Jetbrains IDEs while Wakatime has impressive support of IDEs and editors.

In CoderMirror data is stored locally in a SQLite database, so there is no limit to the data range you have access for free. Because of that, you can always write an ad-hoc query or export to the tool of your choice for further analysis when default reports don't match your needs (I'd be very interested in hearing what kind of reports developers need).

The focus of CoderMirror is on collecting data that can support a methodical continuous improvement effort. I try to create reports that give objective data for personal retrospectives to measure what works and what doesn't for you.

Along with time tracking collects data on what libraries you used and creates personalized quizzes with spaced repetition that attempt to deepen your understanding of the libraries you use.

This is in early stages and limited to Java projects and is the area where I want to focus in the future. Currently there is material for Java standard library, Spring framework, JUnit, etc.