Is this Firebase Security Rule Enough for my Use Case?

Question

I want to use the same data structure as the official Firebase sample as shown below. If I use the following Firebase Security Rule, is it secure enough? My goal is for each user to ONLY have access to the groups they belong to. BTW, I'm using email and pwd authentication

{
    "rules": {
        "users": {
            ".write": true,
            "$uid": {
                ".read": "auth != null && auth.uid == $uid"
            }
        }
    }
}

https://docs-examples.firebaseio.com/web/org