Treto, you are very accurate in your post but I will add this for US based investors. The danger of the ADR involves both premium risk along with currency risk. US buyers of the underlying will not have exposure to the premium risk but STILL exposure to the currency risk. The trend of the Euro vs the US Dollar is and appears to continue lower causing losses for US holders of any Euro based investment.
US based buy and hold investors in late March of 2008 and still holding BIR.IR have less that 1 ½ percent of their original investment based on the share price. The change in currency since that time has reduced the value of their position by an additional 20%.