The module shows signs of maintenance, ie a release history ...
I really like to check a module's changelog looking particularly for this:
- evidence that input from others has helped improve the quality and/or feature set of the module
I see this as a direct reflection that:
- people are using the module and pleased enough to want to improve it
- the module author cares enough about the module to respond well (even to ego bumps)
- the module is evolving into a better implementation under the best testing - use in the real world
In the absence of a maillist archive for the module the changelog is a view into how well the module/author/user has succeeded in the real world. This helps me feel good about how well it will succeed in my world.