We got one... liked it... got a second!
We have not really used our oven since getting them .
We have the ninja dual drawer jobby, and the instant pot duo lid thing with the pressure cook lid and the air fryer lid.
Between those, for two adults, there is never a need to use the oven and when my kitchen is re-done, we won't replace the oven (but we might get a combi microwave).
We do a lot of frozen stuff - however also a lot of from scratch and then batch cooked and frozen things.
Speed - not reallllllly an issue, it is a bit quicker in most cases, but i got them as it seems frivolous to put the whole oven on to cook half a tray of something!
Think about how often you actually use the whole oven - if thats most meals and you're almost never heating up the oven for one tray or half a tray of something, then no they probably won't be the miracle kitchen gadget many say they are.
Having the ability to pressure cook and airfry (either two lots at the same temp or two different things) across the two gadgets, plus a microwave and hob, we can cook anything you could cook with an oven.
It does take a bit of getting used to vs oven cooking, the order you might do things in - but I think that would be the same as learning to get the best out of any new gizmo.