Abba, Father is a collection of conferences by Fr. Bonaventure Perquin, O.P. on the spiritual life in relation to God the Father. It is well suited for spiritual reading. I found particularly inspiring the treatments of discipleship to Jesus, the indwelling of the Trinity, and the authentic motives for pursuing holiness.
In terms of style, I was surprised by how regularly I thought while reading the first half of the book that it must have been composed with the help of index cards, as described by Antonin Sertillanges in The Intellectual Life. The second half of the book, however, seemed to flow more smoothly.
At first, I was not particularly impressed, but after having finished it, I have a fairly high opinion of the work. I would certainly recommend it to those who are looking for good Christian spiritual reading and who can handle a bit of speculative thought. Some might find it a bit too intellectual for devotional use, but the insights are often very penetrating. Reading this book could help many people develop an understanding and approach to the spiritual life that is more clearly ordered to God the Father.