It's difficult to summarize a commentary as detailed as this in only a few words, so I will focus here on just a few short passages in this fine book from Guthrie.
First, on Paul's use of triumphal imagery (a word-picture that draws from the Roman Empire's victory parades): Guthrie makes a strong argument that "Paul actually distinguishes himself and his ministry from those who 'are being destroyed,' who are spiritually aligned with death, a point that speaks quite loudly against the interpretation that he sees himself as represented by the captives in the triumphal procession." I'm not entirely convinced, as I think the "captives" interpretation agrees with Paul's theology of suffering in 2 Cor (and throughout his letters, for that matter) in ways that remain underappreciated in the church; but Guthrie's argument may yet change my mind as I continue to reflect on it.
Second, concerning Paul's statement that "as long as we are at home in the body we are absent from the Lord" (2 Cor 5:6): I appreciate Guthrie's sensitive treatment of Paul's theology here. He skilfully unpacks what Paul is (and is not) saying by using words like endēmeō ("to be at home"/"in a familiar place") and its opposite, ekdēmeō (to be away, in an unfamiliar place; the alien-ness of this term could have used more elaboration): "So long as Paul is 'at home' in his mortal body, he is 'away from' the presence of the Lord. This does not mean that Paul doubts the presence of Christ, through the Spirit, in the believer's life prior to death or at the parousia [the return of Christ]," but rather that our relationship with Christ "will change both spatially and qualitatively at death and will be consummated at the resurrection from the dead." As I've been wrestling with this passage in Paul, personally and theologically, off and on for the past few months, I deeply appreciate Guthrie's thoughtful engagement with what Paul means by absence and presence.
Third, one of Guthrie's introductory statements proves helpful throughout the reading of the commentary as a whole: "one approach to grasping the book's reason for being is to analyze the relational network reflected in its pages." This is put simply enough, but Guthrie unfolds this statement into the relationships between (1) Paul and his God, (2) Paul and the Corinthians (in keeping with the ministry and sphere of influence God assigned to him: 2 Cor 10:13-14, as Guthrie notes), and (3) Paul and his opponents at Corinth (including, of course, attendant disagreements about what true apostleship looks like). As he begins to chart the ways in which these relationships intertwine and inform one another, and the ramifications of each, we begin to suspect what the rest of the commentary goes on to prove: Guthrie is offering us a reading of 2 Corinthians that will keep us prayerfully reflecting -- and faithfully responding! -- for quite some time.