i had a go in one of these machines a couple of years ago and didnt think it much use.
as an instructor with about 2500 R22 training hours , yes it can be difficult to hover - but it was designed to be a private machine for high time pilots.
it does make a reasonable trainer for people who want to go further i.e commercial etc but for hobby pilots i prefer the schweizer 300cb - a dedicated trainer that is easier to hover etc.
the tethered heli is not much good as it dumps the student in at the deep end with all 3 controls and with little understanding of how they work. i always do 5-10 hours upper air work before starting hovering so the student gets an understanding of the controls
the machine i tried incidentally at the time was only about £15K less than an R22, needless to say my employer didnt buy one!
also as the uk caa wont acept any time done in the machine it is difficult to sell the idea to students