Raymond Brown is one of the best scholars on John's Gospel and I found his two-volume commentary too expensive, so this is excellent for me. It provides a summary of his work on John's Gospel and the Epistles, and I wouldn't be without it!
Not only do you get a good, concise commentary on the Gospel and Letters of John, but you also get the text of the New American Bible. For those not in the know: Raymond Brown was Roman Catholic and so it is fitting to include the text of a Roman Catholic bible transaltion used in the US. The ecumenical RSV would have been better, but that is here irrelevant. The commentary is very insightful and will certainly be enough to satisfy your hunger for the time being. The introduction puts things nicely into perspective and gives you a good basis from which to begin your exploration of the bible texts. It is a great pity that books no longer seem to be "Anglicised" - US spelling and grammar is sometimes a little distracting and the former unfortunately seems to be polluting British English. But that aside. You will not regret purchasing this book. Raymond Brown was an expert on John - this book should certainly whet your appetite.
A very useful and readable summary of Raymond Brown's interpretation of the Gospel and Epistles of John. The text is printed alongside the commentary which is very useful and there are plenty of references and cross-references in the margins. The Introduction is concise but comprehensive. In short, for just over 100 pages, there is a wealth of stuff to learn and reflect on in relation to these key writings from the early Christian era.