I remember as a child browsing through the first volume of Dr Barclay's commentary on the New Testament, while in the local Church-run bookstore. It made the life and teachings of Jesus lively and interesting, and in such simple and down-to-earth language that even I could understand it ! So I bought the book, and eventually went back for the rest of the volumes on the New Testament Gospels. Anyone who has difficulty in understanding the Christian scriptures, or relating their relevance to their own lives (probably most people), will benefit from reading William Barclay's commentaries on them. They benefit from the input from both his own considerable scholarly knowledge of the subject and his experience as a lifelong active Christian. Believers and sceptics alike will benefit from reading these commentaries on the compiled accounts of the life and work of Jesus.
I have read many commentaries and Barclay and John MacArthur are the best in my opinion. Barclay is the easiest to read. He aims at the people to which it is written, the culture in which it is written and the language at the time. Barclay is the most quoted in terms of history. Very, very interesting reading.
William Barclay doesn't try to cram his beliefs down your throat. He has an in depth knowledge of Greek and explains the various possible meanings. He gives the meaning that he thinks best translates from the Greek, but allows for other possibilities. I, as a layman, have learned a lot from this series.
Barclay might not suit the more modern or younger writer but I personally enjoy his conservative approach. He does make numerous references to the original Greek - which he should and he cross references to a number of different writers. I don't think he is every one's cup of tea but most of his commentaries as short and to the point, easy to read but definitely a study resource as apposed to picking up a book to read.