An Introduction to Christian Theology, to be sure, is quite a pedagogical feat. More specifically, condensing 2000 years of (mostly Western) Christian Theology into moderately accessible 600 pages of reading. However, it is its versatility that I find is its most praiseworthy feature. Though more systematic in its approach, the historical chapters are crucial to its argumentation. Although it is an introduction/reference — therefore, not limited to be read linearly — I wish its historical chapters (Part III) were either prior or sparsed through its systematic chapters (Part II). Its prolegomena (Part I) is also helpful and well worth the read.
Not everything Plantinga, Thompson, and Lundberg wrote I agree with, and I do not have to. Some chapters really show their cards and impress their biases (e.g., social trinitarianism, sanctioning mutability for the doctrine of God, and kenotic Christology), and other chapters are more distant (perhaps, much less is at stake for them).
$35 might seem a steep price for a book, but it is actually cheap for a theological reference/introduction.