Let me add to add to Zeiss Fan's comments, but first another vote for the Iskra.
The first version of the Isolette III had the notorious Agfa bellows, that if not already replaced, they need to be. The best lens shutter combination for the first version of the Isolette III was a 85mm/4.5 Solinar/Synchro Combination. The 85mm Solinar isn't as sharp as the lens that replaced it. The Solinar is a Tessar design.
I have a photo of the first version at the top of this
web page. Pay attention to the winding knob and depth of field scale at the top of the camera.
My recommendation when comes to Agfas is to stick with the second version of the Isolette III, which I'll call the second series.
Agfa bellows improved with the second series of Isolette III cameras. The second series Isolette III also is available with the better 75mm/3.5 Solinar. The second series Isolette II and III is easily identified by their milled winder and film reminder knobs. The dept of field scale has been moved to the lens.
Be aware that in addition to the uncouple RF, you must wind the film by using a ruby window when using an Isolette III. Put the two together and you have a slow shooting camera that is difficult to wind film with in dim light.
The Agfa Super Isolette, its Soviet cppy the Iskra, Zeiss-Ikon's Super Ikonta III and IV' are much better shooters for modern photographers. All four have coupled rangefinders and automatic stops with regards to film winding. Both the Super Isolette and the Iskra have unit focusing, which improves sharpness close in, 3 to 6 feet.
The Iskra has the best viewfinder of this group of old school European folders. While the Iskra isn't as well executed as the original Agfa Super Isolette or the Super Ikontas, it is no slouch image wise. If you get an Iskra, do buy from a reputable dealer like Fedka that allows for easy returns.