I've had a Flip 3 for about a year and I honestly love the phone, but more for the style/fun factor of the flip over the actual usefulness. I was a huge fan of flip phones in the feature phone era and hated having to switch to candybar, lol, so I had to give it a try!
Pros for me:
Looks very cool, flip phone nostalgia value
I have some mobility problems and being able to set the phone on a table to use it as opposed to having the weight stressing my hands is nice
Great for reading ebooks in a 2-page view
Can see notifs, quick check music, dismiss alarms etc without opening
Fits great in small pockets
Cons:
This particular model is so ridiculously slidey on the outside that it won't even stay still on a level table so a case is 100% required, but hopefully other foldables will avoid this lol
Relatedly, not exactly a big case variety for this style of phone
worry of "what if the screen cracks" hanging over my head
It's been a fun purchase, but I'm not completely sold on the necessity or usefulness yet. If my screen is still okay by the time I'm ready for a new phone in a couple more years then I'll call it a good purchase. So far I haven't had any problems or signs of issues at the folding point, hopefully the trend continues, but I do make a point to leave the phone open most of the time when I don't specifically need the folding functions.