The libpq library is very well designed. I've used many other database APIs (OCI from Oracle, DBLibrary and OpenClient from Sybase, and ODBC) and none have compared to the simplicity offered by libpq. Other database APIs may offer a few more features, but these generally come at the cost of greatly increased complexity.
I encourage you to try the sample applications in this chapter. Feel free to experiment. I haven't covered all the libpq functions in this chapter, only the ones you are most likely to need in your own applications. Explore the library; as you will see in the next few chapters, libpq is the foundation on which most of the other PostgreSQL APIs are built. The better you understand libpq, the easier it will be to work with other APIs.