In a book this size, not much more is possible than an overview of the book and some speculations about the epistle's form, author, and audience. Stibbs goes to quite an effort to substantiate the traditional view of Petrine authorship and time frame. He suspects that Silas (Silvanus) did most of the actual writing at Peter's instruction and added a more polished Greek style than Peter could have produced. In terms of format, he put forward that the book bears similarity to pre-baptismal training material, and he even quotes one expert who feels the epistle is a baptism liturgical text.
The commentary strikes well at the level of informed lay student. It did allow me to have a good review of I Peter.