Informative, conversational, succinct... and intensely important.
This book does exactly what the title suggests. It introduces the Holy Spirit in form, function, and personality. (All heavily backed by scripture, along with hermeneutical underpinnings.)
As an unadvertised bonus, somewhere into the second half of the book, Bevere gives one of the best and most comprehensive explanations I've ever seen on the gifts of tongues.
(I do recommend the audiobook, as it is narrated by the author.)
If you are a Christian from a denominational background that largely ignored (or seemed scared of) the third person of the Trinity, this is a great resource.