Aquinas (Arguments of the Philosophers)
Eleonore Stump
Routledge
I am working my way through this book in a reading group.  It isn't bad.  For the most part, Stump's exposition of St. Thomas' thought is lucid and insightful.  She leads the reader through the dense thickets of St. Thomas' thought, and is able to answer many of the traditional criticisms with grace and insight.

However, there is a great deal of historical background and tradition that she omits, which might help shed light on certain obscure areas.  For instance, in the chapter on divine simplicity, no mention is made of Pseudo-Dionysius, or the nearly 1000 years of apophatic theology that provide the foundation of St. Thomas' analysis of the simplicity of God.  It seems odd to not mention this, to give some context to the discussion.

In other places, I am not sure from where she's getting her information -- for example, in the chapter on goodness, she makes reference to two questions in the Summa that she claims show that the precepts of fortitude have to do with fear of the Lord.  However, when I looked up the questions, they made no such reference.  Very odd, given the general lucidity and clarity of the rest of the work.

Again, it's a decent introduction to Aquinas' thought, although readers might want to consult some other guides to get a better sense of historical context when reading this book.