Instead, it seems they're really 40 Eur thrown away.

The damned thing does not work, either with E51, E90 and N810. I could insert it into the E51 slot by extracting the pcb out of the plastic shell, thus exposing a longer stem for the microsd-like contacts.
No joy, though.

When I connect the Mobidapter+the usb stick to a phone, the leds soldered to the board (which by the way are exposed only when the plastic case is opened) light briefly, and also the usb stick led lights for a second or so.

No device recognized the external flash memory.

Furthermore, after a brief experiment, the battery of my N810 got almost flat discharged.

I bet that the microsd contacts don't allow enough raw Coulombs times second for the Mobidapter circuit and the usb stick to work, and maybe there's the risk that an excessive current drawn from the thingie might damage something.

I don't know if this is a problem of the unit I received, or the Mobidapter is a prank... However, I can't advice the purchase of such a gadget.

I'll try to get a refund