The Resource Description Framework (RDF) is a suite of W3C specifications; consequently there is much information available on the Internet covering both the formal detail and related background reading.
For readers new to RDF, "Practical RDF" stands as a good companion to these online documents (it helped me no end); it introduces the concepts (triples, graphs, commonly encountered schemas, tools, query languages, implementations, etc) and provides a useful base narrative from which to read around the subject.
For a first edition the online errata numbers very few errors and I'd not been inconvenienced or led astray by any of them.
To my mind the letdown for this book is the index - and this is true of many books from this publisher. This is an XML subject and consequently namespaces are everywhere, so when I want to know (for example) about the "type" element, I want to look under "T" - I don't necessarily know or care what namespace prefix it was under when it was indexed, so the fact that "type" is indexed under "R" (for "rdf:type" which is therefore a very long and messy index section) and not also under "T" is a constant niggle.
Consequently as a reference for the more experienced RDF practitioner, "Practical RDF" is not as useful as a good search engine, however, notwithstanding this publication-specific snag, I can confidently recommend this book to the newcomer, who will appreciate it's cohesive coverage of what is (in places) a highly complex subject.