This book is still treated as good introduction to the Holy Spirit (for example, by the online Oxford Bibliography on the Spirit) but I feel like we need something better. I don't envy the task that Schweizer took on here. The vast amount of primary material is daunting without even taking a look at the secondary literature!
Overall, I think the book works but it has significant issues. One is that the biblical ideas of the Spirit are drawn into a sort of 'romantic' take on life and its mysteries. Another is that the texts are often read through a paradigm of tradition vs. innovation which seems to be motivated by the modern Pentecostal movement. I think he also significantly overplays the adoption and influence of Stoicism in the Intertestamental period. These issues matter...but is there another book which succeeds further in introducing the biblical Holy Spirit in less than 150 pages?