In reply to PaulJepson:
Had one a few years.
Quicker than cooking in an oven. No idea what's cheaper. I'd assume the air fryer, but my over is gas which is something like a quarter of the price of electric so you might find it balances out. If you have an electric oven then it's a no brainer. I also assume peak demand of the air fryer is less so maybe still be cheaper than a gas oven.
I find stuff tastes better in the air fryer. Probably down to texture. Moist on the inside, crispy on the outside. Ovens cook slower so if cooking things like skinny fries it either dries them out or they're soggy.
They're no good for things like battered fish. Too bulky and will burn before they cook. Better for things like chips with a high cross sectional area.
Don't try to warm up prawn crackers in one. They float to the top, hit the heating elements and then catch fire. Trust me, you don't need to confirm this for yourself.
Hardly ever need to clean the thing, and when you do it's less effort than cleaning an oven.
I'd suggest getting one.