Tony Hoekema is known for doing Reformed theology in a clear, concise manner. This volume is no different. Read it alongside the Gaffin volume I reviewed earlier this year.
The point of this book is to combat the idea, rampant in charismatic and Pentecostal circles today, that one needs a "second blessing" of the Holy Spirit in order to be a truly mature Christian.
Hoekema puts this idea to bed. He teaches clearly the Biblical teaching on what baptism of the spirit is (it's not a second blessing), and why we shouldn't pursue the speaking of tongues today.
Alternatively, Hoekema teaches, we ought to pursue the fruit of the Spirit and the fullness of the Spirit (see, for example, Eph. 5:18).
There's nothing groundbreaking here. It's a good review of what you (ought to) believe and why. Would of course be helpful if you came in contact regularly with charismatics.