You get a lot of features for very cheap compared to other systems. That's the best way I can describe it.
Bazel is basically cross platform out of the box if one is careful with it: that includes a consistent build organization across platforms, cross builds if configured, and so on. It can build a library declaration for mobile and desktop and embedded and web in a single workspace; try that with CMAKE.
Bazel has a universal package system (e.g. download an archive or git repo) that allows for custom ecosystems (yes some of which are not great yet) to exist regardless of what is normal that ecosystem. This is especially notable for C++ where using CMAKE as a package system is a nightmare, with bazel I can just download any C++ repo off the internet and ignore it's CMAKE file for my own BUILD file. Also notably it's the first build system for C++ that hasn't required me to build or configure boost myself, someone can run bazel build against a repo of mine with boost in it without even knowing what boost is and it just builds.
Which brings me to hermeticy and reproducibility. If one is careful running bazel it always uses the same code for a platform (I've never had or seen weird "on my machine" issues with it which is impressive; reverting/stashing changes has always gotten people a working build again). All of the sources are version pinned, and so on. Getting to hermetic takes some work, but it's possible which is nice. A side effect of all this is my instructions for a bazel project are usually: install bazel, run build; and it just works! Yes parts of the ecosystem suck and break this, but that's a work in progress.
There are other features, like the query system, the test runner, the macro system, the local override idiom, the parallel build. The point is it really is a build tool for whatever needs to be built, however it needs to be built, and not just a scripting language useful for building things.
Bazel is basically cross platform out of the box if one is careful with it: that includes a consistent build organization across platforms, cross builds if configured, and so on. It can build a library declaration for mobile and desktop and embedded and web in a single workspace; try that with CMAKE.
Bazel has a universal package system (e.g. download an archive or git repo) that allows for custom ecosystems (yes some of which are not great yet) to exist regardless of what is normal that ecosystem. This is especially notable for C++ where using CMAKE as a package system is a nightmare, with bazel I can just download any C++ repo off the internet and ignore it's CMAKE file for my own BUILD file. Also notably it's the first build system for C++ that hasn't required me to build or configure boost myself, someone can run bazel build against a repo of mine with boost in it without even knowing what boost is and it just builds.
Which brings me to hermeticy and reproducibility. If one is careful running bazel it always uses the same code for a platform (I've never had or seen weird "on my machine" issues with it which is impressive; reverting/stashing changes has always gotten people a working build again). All of the sources are version pinned, and so on. Getting to hermetic takes some work, but it's possible which is nice. A side effect of all this is my instructions for a bazel project are usually: install bazel, run build; and it just works! Yes parts of the ecosystem suck and break this, but that's a work in progress.
There are other features, like the query system, the test runner, the macro system, the local override idiom, the parallel build. The point is it really is a build tool for whatever needs to be built, however it needs to be built, and not just a scripting language useful for building things.