I came across this ereader because I happen to follow the calibre version updates. Wolder are a consumer electronics company based in Spain. Besides the MiBuk (their first ereader under their own brand) they also have several portable TVs and DVD players. I hadn't heard of this particular model before, but I do recognize the hardware.
It's not really fair to call it a clone of the Ectaco Jetbook, though. It would be better to say that the MiBuk, Jetbook, and the Aluratek Libre are all based on the same original Chinese design, the M218A.
This ereader is based on a 5" LCD monchrome screen, yadda yadda yadda. Really, the one important detail is the ebook format support which includes Adobe PDF, as well as EPUB, FB2, MOBI, RTF, TXT, PRC. It's not clear whether thus ereader has any DRM support. The MiBuk might be using FBReader instead (which could be an improvement if implemented properly).
The MiBuk is scheduled to be available in May. Retail is reported as 159 euros ($214). This is rather expensive IMO, considering that you can get the Aluratek Libre for $120.