The monospace is kind of okay, I guess, but considering the competition there's nothing special about it. Many users will be coding with colour keyword support anyway, so the idea that it's going to be super-great for Go code is strange.

I found the proportional font really hard to read.

It's not as if Google can't do good typography:

https://fonts.google.com/about

So this seems like a rather self-indulgent and not wholly successful side project.