Kind interviewers. They do test you on your knowledge, so make sure you know your expertise. They gave me a mid-interview exercise, like here's a blog post -- write a tweet to promote it. It's not hard if you've done this before.
You will be assigned a recruiter who will help you through the process. There will be ~3x 40min interviews with different leads from the function you're applying for. You'll be asked questions relating to Google's key candidate values.
Lasted over a year. Pretty ridiculous. Very little communication in between steps. Didn't feel like there was any valuation of the candidates time. They really need to figure this out.