Kelly James Clark's Cambridge Core Element, God and the Problems of Love, is open access until December 12. A few parts are interesting, but overall it is not very good; there are a number of peculiarities in the argument, and a few significant inaccuracies.
One of the major problems is that Clark's understanding of Perfect Being Theology seems to be defective. Although he does give an accurate brief summary of it, in his actual discussion, he seems sometimes to conflate it with what is usually called Classical Theism; they are not quite the same -- Classical Theists can accept a Perfect Being Theology, but not all do. Perfect Being Theology is a relatively recent approach based on the notion of God as 'Perfect Being'; it could only be an approach developed within the previous couple hundred years because God as perfect is not a natural starting-point for any kind of theology conducted in Latin and Greek (where all the relevant words usually mean that something incomplete is completed). That God is perfect is a traditional view, but because of the languages, theologians had to be extremely careful about what they meant by that, so you wouldn't start there. Perfect Being Theology really presupposes Cartesian revival of the ontological argument; the Cartesian notion of God as 'infinite perfect being' is really a precondition for this approach. Thus Thomas Aquinas, for instance, while accepting a sense in which God is perfect, does not have a Perfect Being Theology; he would in fact regard it as a presumptuous approach to theology that violates the basic principle of remotion that he shares with Christian Neoplatonists.
Clark's account of impassibility as derived from the concept of perfect being is off. Most Perfect Being theologians take impassibility to be primarily about being immune to both suffering and being forced to undergo something (because this is what the word literally has always meant). Clark wants to follow the very narrow and not, I think, standard view that it is primarily about certain kinds of feelings -- God does not have disturbing feelings. I think this ends up confusing things. The primary reason God does not have such feelings, at least in our ordinary sense, is that he is incorporeal, and all our feelings in the strictest sense of the word are (as the word suggests) corporeal. Impassibility does also imply that God experiences no passions; this is because 'passion' means a way of being modified by the world. If you get punched in the face, you experience the passions of pain and anger, which are as it were forced on you by the punch; God cannot be forced in this way. (It does not follow that what is a passion in us cannot have a non-passive counterpart in God, which is actually quite important; more on this in a moment.) I suppose the 'disturbing' could be trying to capture this -- God cannot be disturbed, 'being disturbed' could be a way to talk about passibility. But I think most people would take it a narrower sense than this would have to mean. And it's clear that Clark himself takes 'disturbing' to indicate certain kinds of personal relations. Perfect Being Theology does not imply that God cannot be actively related to us in various ways that in us are passions; what it implies is that when this is the case, God does not have them as passions. They are not things He is made to undergo; they are things that He does.
One of the reasons to insist on this is that it is entirely possible for a Perfect Being theologian to hold that God has compassion; compassion in us involves passibility, but it's very common to argue that there is an active component in it and that compassion in us and in the form of the passible imitates what in God does not involve passibility at all. (On this account, our usual need to be moved to compassion is actually a defect; God does not need to be moved to be compassionate. As Muslims would neatly put it, He is Compassionate and Compassionating. We can only be sporadically compassionate, precisely because we have to be moved to it; not being passible, God's compassion is constant and inexorable.) To be sure, if you insist on using 'compassion' in exactly the sense that it is used to apply to human beings, then it could only be a figure of speech when applied to God; but it's generally accepted, by more than just Perfect Being theologians, that we can use the word 'compassion' to describe something not involving passibility at all, despite the fact that our own particular version does.
Clark also distinguishes love of benevolence (willing another's good) from love of compassion (empathizing with another). He at one point treats this as if it were exhaustive -- he concludes that divine love must be love of benevolence because God cannot have love of compassion -- but it is very obvious that these are not exhaustive. One reason that this is important has to do with the fact that discussions of impassibility in the context of this topic are almost all concerned to argue that God does not have craving-love (amor concupiscentiae, in the older terminology). This is the primary contrast with impassible love. Clark treats impassible love as primarily contrasted with love of compassion; but as previously noted, it's quite common to hold that God has a kind of love of compassion (based on His divine omniscience), just not our kind of love of compassion (based on animal empathy). And this is not surprising; using 'empathy' in the sense that Clark uses it is historically quite recent, and while there are some ways of talking about compassion that easily fit under what we call 'empathy', this is not true of everything people have said about compassion. The Bible and the Quran do occasionally use terms of God that suggest something like what we would call empathy, but every clear case is one where they are clearly using corporeal terms of God, and therefore (as usually interpreted) are speaking metaphorically. This is because the old words for feeling what another feels (and indeed many more recent expressions) are all very, very physical, having to do with the feeling of your kidneys or your belly or your heart. These terms are meaningful; but they are meaningful in the same way that expressions like 'the arm of the Lord' are meaningful, and for exactly the same reason.
This has some effect on how to evaluate some of the things Clark says; for instance, that the highest form of love is compassion. Maybe (although some might argue that the highest forms of love are creation and salvation, and in our case the highest form of love is to will the good of another even to the point of dying for them), but we know it's not going to be in the limited, defective ways that we experience compassion, and therefore we already know that if God has this kind of love, He has it in a better sense than we do.
Likewise, although this is more to do with traditional forms of things that we usually call 'Classical Theism' rather than the more recent Perfect Being Theology, Clark seems to misunderstand what the via negativa implies about metaphorical expressions. It does not, as Clark claims, imply that every metaphor about God can be cashed out in non-metaphorical terms, so that God has to be understood 'shorn of every metaphor'. It is entirely consistent with Classical Theism and Perfect Being Theology alike that metaphors apply meaningfully to God (in fact this is required by most forms), and it is entirely possible for someone to say that in some cases, metaphorical expressions are our best ways of describing God so that we can't cash them out into a better non-metaphorical expression. What is required is that we understand such metaphorical expressions as metaphorical expressions. Nothing about the via negativa prevents this. (In fact, historically the via negativa has been very metaphor-friendly, because as long as you recognize that they are figurative, it's easier to recognize the imperfections of our labels.)
I won't discuss Clark's discussion of hell, which is just a complete muddle, beyond pointing out that he says several false things. (To take just one example, he mischaracterizes Aquinas's account in ways I've talked about before. [ADDED LATER: I actually intended to link a different post.)
