Honestly, I had a really great experience from beginning to end.
Here is a recap of what I experienced firsthand.... I applied online after hearing about some of the new projects that GitHub is working on. After my application, I received an email from the recruiter and I scheduled a video meeting later the same week. She spent about 30 mins getting to know my background and asking some traditional questions.
I scheduled a take-home assignment. Overall, it was a fun assignment. A couple of days after submitting my pull-request I received an email from someone to schedule meetings with technical staff and the hiring manager. Overall, the people I met were great and appeared to be highly capable. The hiring manager was eccentric but I warmed up to him by my second meeting with him.
After a week, I spoke with the recruiter. It turns out that they didn't see my experience inline with what they were looking for. She did mention something about a "no- feedback" policy -- but in my experience, all of the technology companies have the same policy (Google, Facebook, Slack, etc.).
OVerall, it was a good experience -- even if I didn't get the job.