Obsolete before it hit 1.0. While grunt/gulp was fun for a while... i am not looking back to our 800 line grunt file, complicated async configuration and the tons of dev-dependencies. Webpack blew everything out of the water. 80 lines of config, hot-reloading, code-spliting, hash-filenames... Looking forward to whats coming next.
Grunt was nasty as hell, and clearly didn't learn any of the lessons from, say, proper Makefiles from the UNIX world over the past 30 years. Gulp is a looooot better, especially when I have things like Foundation 6's zurb-template, which is basically configured out of the box how I setup my Foundation 5 era projects. I don't care how big a Gulp file is if I'm not the one having to do major maintenance on it.
Do authors of these build tools actually sit down for a couple of months looking at things like Makefiles that have been around forever, perhaps even Maven, etc. Take all these things together and go "This is what sucks in all of them, and here's how we can do it better" and still cater for all the use cases that these tools are brilliant at.
It's like there's no thought put into these tools and nothing is built on computer science foundations. Like why are you using Json as the syntax? Ant build files were an abomination and Json really isn't offering anything better (actually way less), except a slightly more readable syntax for trivial use cases.