I was able to pick up, like new, the 1st edition of the original 4 volume set, it is like studying the entire Bible from the perspective of the book of Romans.
I was reading that set not too long ago and finally gave it up in frustration without finishing it. Barnhouse (1895-1960) was a dispenationalist (at a time when dispensationalism had made severe inroads into the Reformed camp). I gave up the set when he made the blunt statement that it was unfortunate that the Reformed had made creeds and confessions so important.
And, as a bonus: you won't get much of an exposition of Romans in that set, either, precisely because he spends so much time ranging widely over other subjects - not to mention all the personal stories he has to tell.
There are many more, better books on Romans to spend your time on. (One suggestion: John R. W. Stott's commentary.)
For alternates to some of the standards generally set out for Romans (Haldane, Hodge, etc.) I can recommend Rev. William S. Plumer, and Prof. John Murray. I believe you'll find both of these very insightful.