I've ordered certificates before directly through the state, and it is a hassle. You have to find the forms, which is pretty difficult. Then you have to fill them out which is not that easy, because the forms are pretty confusing. Then you have to mail them in with a check and other documents... And if you are lucky you get your certificate in a few months.
With fastbirthcertificates you just order online, email a copy of ID, then the certificate arrives. Well, well, well worth the small fee they charge!