The State Department will accept a certificate so long as it bears the registrar's signature, has a raised or colored seal, and the certificate was filed within one year of birth. Obama's COLB meets all of those requirements.
My guess is that LOTS of people have no better proof of birth of being born in Hawaii than Barry does. On the other hand, his mother probably did a lot of stuff that alienated Obama from the United States. Assuming he had a valid claim, did he succeed in establishing that claim before he turned 18?