I found it useful to read through the open and closed issues and estimate what caused the described problems. Look at the usecases that do not work, are they co

I found it useful to read through the open and closed issues and estimate what caused the described problems. Look at the usecases that do not work, are they common or exotic? Does the program fail safely or does it fall back to unwanted behavior? Does a certain configuration cause the program to run amok and wipe your disk? If you get many "wtf" moments while doing this, the project is not mature.