...:)
The comparison to script shipped with kernel (circa 2012):
1) gmil works or attempts to work across many releases
2) gmil works harder to make packaged installable result(s)
3) gmil has a smart way to build many kernels at once / at a keypress
4) the scripts/ _can do most of those steps but _don't combine them, leaving maybe allot to read and type. Details come undone can cause confusion, rebuilds, and missing kernel files.
License: public domain. thanks kernels linux team!