I bit the bullet and got one a while back. Don't use it a ton but really good for some things.
Like dowels or other loose tenons, layout is simplified, and less material is used since no length is needed for tenons.
I worry about the durability of the machine, and about catching the cord and sending it on a fatal plunge to the floor.
It's straightforward to make tenons of matching wood- a good idea for outdoor items.
I disagree that it's too complex for knockoff manufacturing- roto hammers have a similar mechanism, & they are common.