Is it right to promote women using quotas?

Germany's passed a law making it compulsory to allocate 30% of seats on non-executive boards to women, in large companies. Surveys found women remain grossly under-represented in business. This is despite the country having a female chancellor, Angela Merkel.
Germany is not the first county to have quotas, Norway has a 40 percent system. Should other countries be following these examples? Is this an effective way to promote women in business?

Photo EPA