It's an alternate app store primarily for FOSS software, including a lot of stuff that you can't find on the Play store. It's very well vetted and there's zero reason not to use it.

If you want a more specific example of something worth getting on F-Droid, there are several adblockers which work significantly better than anything you'll find on the Play Store, simply because the Play Store largely prohibits apps which directly affect the operation of other apps.

You should use Droid-ify it is an alternative app for F-Droid. It lets you automatically update the apps.

I don't think there's any reason not to use it. It's carefully curated, I haven't come across any malware on it (of course that doesn't apply if you add random repositories). Personally, whenever I need to download an app, F-Droid is the first place I check.

I use the neostore frontend. Definitely check it out if you want material you

My MO is that when I need an app to do something I look for a good FOSS app via F-Droid first. There's a great list of open source android software here.

Some apps in FDroid require root. If you have rooted your phone be careful about those. I haven't heard of any security issues but as a Linux user of 25+ years I'm paranoid about ever giving apps root access.