I had a 3+ I got for a vacation back in 2015. Was not even remotely impressed. The only application it had, for me, was action or underwater video, neither of which I did on a regular basis. It ended up being a one or two shot (pardon the pun) deal. With that in mind, I kept discouraging guys from getting a GP about 2 years ago (and a DJI pocket). Unless you needed the action part (of which it was a no-brainer, though you could go with a knock-off), if you wanted quality video, your phone was a better bet. Spend a third of what a GP costs and get a good smart phone gimbal, and download a quality video app.
Well, the GoPro Hero8 changed all that. I started looking at it when it came out and got one about a month and a half later. I haven't even used my phone since (other than quick shots when I didn't have the GP). Anytime I leave the house for a non-specific task (work, church, etc.), I take my GP. The video quality is good -- just about as good as my iPhone -- and it has a built in stabilizer. I've even used it for what I'd think of as decent video work -- shooting my church orchestra when we did a "Jazz Sunday" a few months ago. Its much easier to deal with than a phone and gimbal. Heck, I've got a Zhylis (sp?) gimbal for my phone that I really haven't used.
The GP9 is even better and I may get that. I wish they had the same battery since I have additional batteries and the external charger, so I may just wait until the next version as mine is just fine. I've invested in some decent micro SD cards and I know I'll need even better (and likely bigger) cards for the next version. I upload videos on FB and am working on doing some on YT; maybe some training ones. I think someone serious can work with the GP, though due to lack of manual options and a fixed lens, you are limited. My 3+ did 1080 but it was so processed looking, it was hardly worthwhile. The 4K on my 8, from what I can tell, looks good.
At any rate, it is no longer just an action camera. I'll be out this weekend shooting stuff.