Headless in Windows is fully supported in Chrome 60, which is now the Beta. Mac and Linux are in great shape as of 59.

I tried it out yesterday, moving our unit tests from PhantomJS to headless. Short answer is it's not fully working yet, the browser still pops up with a blank interface window, but unit tests work as expected.

I tried out the PDF and screenshot stuff, but they didn't seem to be working on Windows yet. Remote debugging is fine, but as mentioned, you get the blank interface window, so it's not really headless yet.