The 1646 edition of 'The First London Confession of Faith' was the confession of faith of seven Particular Baptist congregations in London. It was written prior to Acts of Parliament in 1649 ratifying the Westminster Confession of Faith with its Larger and Shorter Catechisms. The Appendix by Benjamin Cox to the 1646 edition of 'The First London Confession' was also printed in 1646. The writers of the confession and Benjamin Cox were clearly biblically oriented Calvinists on the sovereignty of God and the particularism of elective grace. These two historic Baptist documents exude Christ in the interpretation of Scripture.
The 1646 Confession represents a significant effort by the Particular Baptists to articulate their theological convictions clearly while avoiding condemnation as heretics by the governing authorities of their time. Confessions such as this serve an essential role in defining and communicating the core tenets of faith. The 1646 document, in particular, demonstrates a careful focus on the essentials of Christian doctrine and stands as an important witness to the theological and historical development of the Particular Baptist tradition.
In terms of the confession itself the 1646 1st London Baptist is not as exhaustive and detailed as the 1689 2nd London Baptist. It emphasies things which at first glance might not seem that important for a confession: eg the 3-fold office of Christ. It is not as well written as the 2nd confession which of course borrows its structure (and some of its wording) from the Westminster Confession of Faith and is therefore a lot more polished. The 1st confession also is a lot less influenced by Presbyterian covenant theology for that same reason.
In terms of the booklet itself, I thought the 3 prefaces were very helpfully put it in its historical context and give the reason why there is a need for its republication today. The inclusion of the Cox Appendix at the end is also helpful to further clarify and emphasise some parts of the confession. In some ways the Appendix has clearer language than the confession itself.