William Barclay seems to have fallen out of favour, due to his hope that his readers would think for themselves, instead of trusting to the simplifications of modern bible translators.
This book, like his others, provides his own translation and is rich in background information: the history, language and culture of the region and times when an unknown apostle wrote his letter. Barclay draws extensively on Jewish legend and extra-biblical stories to add colour and insight to his explanations of passages. If you delight in tales such as Gabriel being sent to box Moses's ears, or references to the Maccabean revolt, then you may be fascinated by this book.
Yet despite such interesting asides, the author's love for his Lord and saviour pours through every page, making it a rich devotional, best taken a passage or two at a time.