Peter's letter reads like...well...a letter; it is personal, but in a subtle, thought-provoking way. Peter is writing to friends in the faith, sending them words of encouragement, direction, and instruction; he is passionate about his content, and really wants them to get his point. In reading through this letter, one gets the sense that he goes over the main themes over and over again; we belong to God, we live in hard times, our conduct should honor God and each other. In one sense, it is refreshing to read a letter that stays with a few themes; it is good to soak in a message, let it seep into your soul.
An interesting aspect of this letter is its density; it is chock full of Scripture references - the Torah, the Psalms, the Gospel and Paul's writings. In one sense, Peter is saying very little; he is bringing a full range of Scriptures to bear in on the condition his friends face. He says nothing new, but rather collects for them what has been said already about who they are and how they should conduct themselves in hard times.
What makes this letter additionaly interesting is how Peter weaves his story into the letter, how his story with God becomes a spur for them to let their story merge with God's as well. Chapter two is a fine example of this: it opens with a list of vices to avoid; the very ones that Peter was guilty of as a disciple. Then Peter writes about being a rock of God - which hearkens to his appointment by Jesus as a rock upon which He would build His church; Peter calls his friends "rocks" as well, stones that God has shaped for building a home of shalom out of which praises and gifts are given to God which bless the world.
Peter goes on to cite Scriptures from Isaiah and the Psalms which are a reflection upon how Peter stumbled over Jesus the rock, and how unbelievers stumbled over Peter the rock. And so it goes, Peter reflecting upon the variety of names God has given his people, and Peter both identifying himself as part of that story, and exhorting his friends to stay in the story.
In regard to conduct, Peter again speaks from experience. He knows what it is like to be at odds with governing authorities; based on his experience and the teachings of those before him, he advises them. Likewise for being under the master of another, it is doubtful that Peter ran his own fishing business, bur rather worked for another master. Peter ended up trading a fishing-master for a Jesus-master; and so he advises his friends, though you live under an earthly master, you are truly servants of God, so live in that freedom and bless others. Peter also understands very well the suffering that Jesus endured, and what that means for forgiveness of sins, freedom from unrighteousness and power to do good in God's name; and so he calls his friends to stop wandering and come home to God.
Jesus invited Peter back into the flock, to come under the Head Shepherd and Overseer of Souls; Peter is inviting his friends to come under the same Shepherd and Overseer. And Peter invites you too. Are you straying or staying?