I've got a Foodi Air Fryer/Health Grill thingy.
I would say it's fairly useful, but not a life-changer. I use mine two or three times a week.
I do salmon fillets quite often in mine, it does them very well -- crisp skin and the flesh stays juicy.
Chips, yes -- depends on the type of potatoes I suppose but yes it does chips pretty well.
I do chicken portions in mine too. Chicken thighs work really well. I wanted to cook a whole 'roast' chicken in it, but it's not big enough height-wise -- I'd have to spatchcock the chicken to get it to fit.
It also makes really nice egg fried rice in about 15 minutes.
It's generally good for anything with a skin -- potatoes, fish, chicken thighs.
Apparently you can make good brownies in it but I haven't tried that yet.
It is also better at keeping cooking smells contained than the oven or shallow frying. Very helpful with fish especially. And the cooking parts will go in the dishwasher more easily than my big oven trays.
Downsides -
Because it cooks things quickly you don't always get a lot of flavour, in (for example) rubs on chicken breasts etc. If you can marinade things for a day first it helps, but I always forget.
Mine's only about three months old, and I've found that the ceramic coating on the air fryer pan and the under-tray is already starting to chip/flake off. Shark-Ninja didn't want to know, apparently it's 'normal'. You can buy replacements but that's not the point really.
It is quite big. I have to keep mine on a shelf and get it out when I use it, because otherwise it would take up far too much work surface room.
It's relatively noisy, and I have to use the kitchen extractor because the little fan inside the air fryer blows out hot air and sets my smoke alarms off.