I have a Hero3+ and still use it often.
Pros;
waterproof. Underwater shots.
One of the great things about it is that you can step thru the video and pull HD photos out. You get" ACTION shots" .
Superwide angle lens means you don't have to use viewfinder, just point in general direction and get awesome shots.
Mount it on an old fishing rod and it sits steady in a rod holder ready to shoot.
Cons;
You have to download them to a computer to edit... the new one is probably seamless on a mobile app and newer phone so that probably doesn't apply anymore.
You might literally spend hours pulling photos and making videos...follow the link to my youtube page for examples.
Here's one...a trip on my 265 Express