Nobody can write like William Barclay. His style is lively, quotable engaging and enlightening. DA Carson said of him the he could not be boring even if he tried to. The historical backgrounds he provides to the scriptures are invaluable.
The only drawbacks are
1. His theology tends to be off track in a number of places. He sometimes propagates some really heretical views. If one is able to read discerningly, then these volumes will be a real asset to your studies.
2. This revised editions have cut out so much of the material in the original. If you find the original publications in a used bookshop, do not hesitate to purchase them, you wont regret it!
Other than that, this is a great set that I eagerly recommend.