Teaching people to manipulate the controls of a helicopter in the cruise is relatively straight forward and, in a stabilised aircraft, teaching someone to hover isn't that much more difficult.
However, getting from cruise to hover and landing is usually where it goes wrong for the inexperienced.
I have taught many RAF rearcrew to fly (in the old days with single pilot and a navigator that was quite useful) and some were very competent.
However, we had an incident a few years ago when a helicopter pilot did slump across the controls and it took the co-pilot several hundred feet to recover - had it happened lower, they would have been toast.
In short, know your audience and consider carefully the implications of them suddenly putting in a random control input - a favourite is lowering the lever and pulling back on the cyclic in the hover!
Definitely not recommended in anything with Robinson on the placard!