How to How to evaluate an application? Is it worth spending time or money on?

It depends. I mostly buy applications nowadays to get things done quicker but then at the same time have Netflix subscription where hours are lost.

Evaluating an app's worth hinges on retention over time spent. High retention signifies user value and engagement. Consider market fit, user feedback, and financial metrics for a balanced assessment. If users return and engage, it's likely worth the investment.