AWS Advanced Network Specialist, Anyone?

I posted this in /r/AWS but got no response, hoping I might get more hits here.

I have been using AWS for like five years. Primarily EC2, S3 and R53, but I have used a lot of other services and understand what the majority of them do and how they work.

I've been through the AWS training class done by AWS Training Team and was pretty bored through it as I knew it all (what at least was taught).

I recently stood up a site-site VPN from our on premise Palo to a Virtual Gateway and got all of that working and finally understand all that.

I bought the Official Study Guide for Advanced Networking and thinking about taking that test first. Has anyone here taken it and have any things I should focus on? Obviously, no NDA breaking, but just looking for general help.