Works almost as described. On my Mac I just dragged the app into Applications and ran it, using right click 'Open' to permit an unsigned app. Files came out where expected. Originally gave a 5, but had to reduce my stars. For some images, rather than an image file I get two files, e.g. image-029.ccitt and image-029.params. Not documented. Looked at the code but could find no occurrence of 'ccitt' or 'params'. I assume these are coming from one of the external components he is pulling in. I did find a sleazy workaround. It appears that one of the filters applied to the images within the pdf is missing or not able to be converted to jpg. In the original pdf I replaced occurrences of Filter/CCITTFaxDecode with Filter/FlateDecode and it seems to work. My documents are pdfs of scans of old typed documents.
Easy, simple to use and quickly+properly doing the job.