Main downside, as with many tools much better than make:

>walk is currently not considered stable, and there may be breaking changes before the 1.0 release.

:)

It also needs go, which is pretty non-lightweight dependency on windows, I guess. (And personally, I don't find these dir-hierarchy connection and bash's "case $target in a) ... b) ..." any friendlier at all, though make has some quirks with variable interpolation.)

I'm not to argue to use make for very complex situations, but usual src->intermediate->executable and generate this from that of any size and count is a perfect task for make. Makefiles are unsuitable not for big projects, but for complicated build systems, where it's not enough to just do them steps in correct order. If your build system is complicated, it should be worth it at least. Otherwise use make.

Fix: typos/grammar