I recently was lucky enough to come across a new old-stock(never sold) Hohner36 on eBay and I can give you my opinion.
The construction is quite good and it is better quality than the 32 and 26 key model from that same era and quite different in design. The end caps are plastic but the bottom plate which has a very shallow V shape is made of metal. The melodica doesn’t have any holes anywhere in the body so if you are recording you want to turn the keyboard side towards the mic.
Playing: I have owned Suzukis, Yamaha, new and vintage Hohners, and several other lesser known manafacturers and I have to say that the 36 is the most comfortable keyboard of them all. The amount of key dip and springyness seem just right to me. The other great advantage is that although the body is the same length as other brands of melodicas the 36 notes means there’s room to make the keys slightly wider. You wouldn’t think this would make a difference but it is quite surprising how much more comfortable it is to play on, especially if you are coming from a full size keyboard background.
Where I think the instruments sufferers is airflow. It’s not very even across the keyboard and I have to blow harder and softer in different octaves and there is a bit of delay from breath to note. Hohner’s philosophy seems to be to have air channels instead of blowing straight across the reeds. When you look inside the mouthpiece connects to a long channel that leads down to the highest notes first and then to the low notes.
I don’t want to say too much about the sound, as it’s subjective it does sound quite different from the new Hohners and the vintage 32 note both of which I have tried it against.
If you search on YouTube there are several videos of people playing one.
I hope this helps if you have more specific questions let me know and I will try to answer.