We've got one, they're ok but absolutely not life changing.
I wouldn't buy a Ninja personally - I ordered one directly from them and when it arrived it was scratched inside and smelt of chips. It was clearly a return and the more I thought about it, they must have been selling returned items as new, otherwise how on earth could a used unit end up mixed in with new stock.
I've got an Instant Pot versazone now. It's better than having 2 fixed smaller drawers as you can use it with it without a divider, so can fit larger items in. Each side can still operate independently if you want to divide it in half.
I'm ambivalent about ours. It's great for baking, pizza, oven chips, baking potatoes/sweet potatoes. For roasting veg I prefer the oven - I like to use a really large flat tray and spread the veg out, you can't do as much in the air fryer, even using the whole big drawer. We don't eat meat, so no need to cook a chicken, chops, sausages etc. Chips and pizza only once in a while and only have roast potatoes on Christmas day, so not much use there either!
In terms of cleaning, our is really easy - take out the drawer, half fill with hot water and washing up liquid, soak for a few minutes and then any mess just slides off. Quick brush and rinse, it's done
Overall, I would say it's quite useful, but not at all essential.