If you look on the air fryer thread there's a lot of discussion on there.
I think they sound really interesting, but I also know that given that I never fry anything, very rarely pressure cook anything and the same for slow cooking, that I'd probably never use it.
Probably the most likely thing I would use such a thing for would be pressure cooking, it's probably more automated than the old school pressure cooker I'm too chicken to use.
Basically I'd need someone to come to my home and demonstrate my recipes for me before I did it.
I'm sure there's stuff I don't make now that I might make if I had such a thing. But would I?
Also second T42's comments on the washing up.
Wait a few months for all the unused ones to turn up cheap on Marketplace or Gumtree