The Duaflex is the one old camera that I own which has completely failed to excite me. I have been on a quest to use each and every one of the old cameras that have been given to me (I'm working on it, Donald. The one you sent will be used this month... maybe.) Since my much loved F-in-law gave me the Duaflex, I was quite excited to go out and do it justice. It came to me with box, instructions, flash and flashbulbs. No matter what I did, however, I couldn't get excited about the camera. The lenses were clear, the shutter worked well, the film was easy to get or modify but the entire experience left me cold. As a result, the images were flat and boring. The quality of the lens is no worse than those on many of my other cameras, but it just didn't do it for me.
Point being... I think the experience of using an old camera is dependent on many non-technical factors, your mindset most important among them. If the equipment intrigues you, if the memory of a similar piece of gear in your hands or in the hands of an ancestor brings out the creative in you, if the reaction of the people around you to what is happening becomes a factor; then you will have a good time and make good images.
Quality is another issue. I have found that the best lenses I own are old lenses, much due to the fact that I am... frugal. Consequently, I find myself using cameras that are old without even thinking of them as old. As long as I have a comfortable relationship with the gear, it is simply an extension of my eye. I have a long way to go to build that relationship with each and every one of my cameras, but I know it can be done.
Oh, one more thing. Old cameras are also a disease. Inexpensive, often beautiful in their own right, they lead to G.A.S. (also known as Galli-Oleitis.) The result of this, for an inefficient and forgetful man like me, is the discovery that one has, at any one time, six or so cameras with film in them, waiting to be taken for a walk.