I'm a committed Kotlin shill and a very experienced Gradle user but I'm the first to admit that it is absolutely arcane for those new to it. Once you know all the incantations it's really flexible and performant but good luck writing a plugin for the first time.
My favorite thing about gradle is that the build file is written in the same language as your code. This gives you the great power of easily adding a little hack into your build file, so it's pretty rare you actually have to make a plugin.
The downside is that every build file is a little bit unique, but IME it's not that much worse than what happens in golang. In golang people usually slap a makefile on top of the go commands, and then you have to read the makefile to figure out what targets you need to run, and if it gets a little complicated then they start calling out to shell scripts and things like that. ech.
