I will not make a detailed opinion to the extent that I am fully in-phase with the advice of Nico38: it's convenient, cheap, it works, and I even found this little box has a certain charm. Nico38 as I deplore the lack of USB is the only complaint I would make this product. But hey, at 30 euros it is understandable, a Midi interface / USB costs at least 40 euros alone.
I bought it on Thomann 6 months ago, I see today (January 2008) on the Behringer website it is unavailable in Europe, bizarre, yet it must surely remain in stock at some retailers.
In any case it is ideal to complete a master keyboard that lacks a few knobs and buttons.