Simple C-ish syntax that's relatively familiar to most programmers, write once and compile to/from anywhere without arcane flags, easy to understand and use concurrency model with message passing, reference development tooling that can enforce standards out of the box.
I don't think there is much new here other than removal of cruft.
They bolted on two principal new features: channels and garbage collection. They also added a few hacks, like the two-value return.
And lo, we have a winner based on tech form 1970s and 1980s, with only a small bit of pixie dust from 21st century proper, the advanced GC. Anybody can become productive in a weekend. (Then the productivty ceiling is hit soon, and copy-paste programming ensues, but the initial high is strong.)
The tech was "exciting" because Google released it. Pretty much anything Google releases is coated in magic pixie fairy dust (perhaps slightly less so these days).
Tech like postgres doesn't get that kind of hype.
For most developers it seems to work the other way around - big names and marketed heavily => it has buzz => it must be good.
Under boring there are two types - PHP and postgres. Boring tedious and annoying and boring reliable workhorse.
The 2nd type is my favorite type of tech.