While I can believe the claim it's better than make, it would be way more interesting to see how it compares to Bazel. After using it (or rather Blaze) at Google and now Bazel at Improbable, I consider it the gold standard in build tools.

If anything, I wish Google would open source the rest of the build "ecosystem" that together with Blaze let you build the whole codebase in seconds. It was pretty amazing.