It looks mainly to be pitched as an alternative to Grunt, the current main (I think?) Node.js build tool. And its primary feature seems to be that you don't have to figure out where your intermediate build products go. Beyond that, who knows.

(Grunt, incidentally, strikes me as a system that has learned nothing at all from decades of other build tools. It's about one step better than piping globs to unix commands.)

It's intended for people that are building web stuff with node. So they're already writing everything in Javascript and already have a dependency on node, so using node for their build process eliminates a dependency on Make or whatever.

The incumbent in this niche is Grunt. Grunt has a rich ecosystem of plugins, but it's complex, difficult to configure and difficult to debug. Gulp is meant to be simpler and therefor easier to use.

Gulp is not meant to compete with Make, Maven or the like.