I will argue that yes it has. Of course, these rights are not uniformly or universally observed, but in general you can say that the courts have been very consistent in upholding free speech and religious rights. They have also been, for the most part, very consistent in forcing police and the penal system to observe individual rights when it comes to handling both the accused and the convicted.
The Bill of Rights is meant to protect the rights of Americans; rights like the right of free speech and religion or to be free from excessive searches and seizures. However, the Bill of Rights is not able to prevent the violation of rights if the majority of Americans want those rights to be violated. The Bill of Rights is just a piece of paper. It can only help to persuade people that rights should be respected.
An example of this can be seen in the fact that people's rights were clearly trampled during the McCarthy Era. This happened because the majority was willing to go along with laws that took away freedom of speech and association for communists. There was such a fear of communism that people did not really care if the rights of some were infringed upon. The Bill of Rights was not able to protect communists in that situation.
A similar thing, one could argue, happened to Mormons in the 1800s. They were forced to give up their religious practice of polygamy even though the Bill of Rights says that people should be allowed to practice their religion freely. The Bill of Rights was unable to protect them because their religious practice was frowned on by a huge majority of the people.
The Bill of Rights has usually been effective in providing people with rights. However, it has failed at times to protect people who are particularly unpopular.