From the introduction of Furnish’s commentary:

No Pauline letter requires more of its readers or offers more of a reward to those who apply themselves carefully to its interpretation than 2 Cor. Here one sees the apostle Paul in spirited and sometimes anguished dialogue with his congregation in Corinth, with a group of rival apostles who have intruded themselves into the congregation there, and even with himself. Here one finds Paul writing quite candidly of his sorrows and joys, of his fears and hopes, of his uncertainties and convictions, of his weaknesses and strengths. Here one catches a glimpse of him in Corinth on a short, painful visit; of a tearful letter written soon thereafter; of the dispatch of Titus to the congregation and of Titus’ return; of a financial contribution solicitied and pledged but not yet made; and of the apostle’s expectations about his own impending visit. Here more than in any other letter, Paul offers specific comments on the meaning of apostleship and reflects on its distinctive character and responsibilities. Yet his remarks on this and related topics are not those of a person who has drawn apart for a time of unhurried self-evaluation. Rather, they are the remarks of one who, even as he writes, feels the pressure of his responsibilities for “all the churches.”

….Indeed, the student of 2 Cor quickly discovers that, particularly in this instance, biblical interpretation involves in virtually equal measure historical reconstruction, literary analysis, and a sensitivity to theological concerns. Because Paul writes as one who has been called to preach the gospel of Jesus Christ, the interpreter must reckon with the apostle’s fundamental theological convictions. Because Paul writes as one who understands the gospel to require important behavioral as well and attitudinal changes in the lives of those who accept it, one must also reckon with the social and historical realities the apostle and his first readers are facing. And, finally, one must be alert to the writing itself, to its overall literary form and structure, and also to the lexical and grammatical details which help to clarify Paul’s meaning. Especially in the case of 2 Cor, no one of these tasks can be carried on in isolation.