I have never had the opportunity of ownership but would certainly go for one if I had the chance (space allowing). It's one of those rifles that came more to our attention in 1977 with the launch of Airgun World and the enlightenment that the magazine brought along, also bringing to our attention many lovely, legendary airguns like the Weihrauch HW35, BSF B55, Original 35, Feinwerkbau Sport & 300 etc.
My impression of the Haenel would be of a slightly more austere but solidly made, well-engineered, dependable and accurate break barrel. Enjoy.