I think it looks useful and hopefully they succeed. The Valoi includes its own light source, unlike the ES-2. Of alternatives, the Nikon ES-2 has always struck me as rather expensive for what it is. There are a zillion slide copiers out there left over from the film era, but at 1:1 they aren't ideal for scanning 35mm, unless you own a full frame digital camera, plus they are rather slow optics (some usability issues like needing a bright light to focus, etc). Setting up a copy stand accurately for DSLR scanning is harder than it seems and takes space.
DSLRs depreciate rapidly due to upgrade fever and the bottom has mostly fallen out of that market, so if one had this device and a macro lens, an APS format DSLR body would be a relatively inexpensive part of the setup.