Steve Hays does a great job, so for a detailed response, see his comments. I'll add a few thoughts of my own by way of supplement to what Steve has already said.
Wes Widner states: "Middle Knowledge (and William Lane Craig in particular) does not teach that God's soverignty is trumped or determined by man's free will or by God's Middle Knowledge of man's free will."
Yes, it does. Consider Craig's claim:
What I am simply saying is that God's aims in this life, in this world, are for a maximum number of people to come to know God and His salvation as fully as possible. And it is possible that that would not be achieved in a world that did not involve as much suffering and evil as this world does. Far from being counter-intuitive, I find that very plausible.(source)
That's at least a conditional trumping claim. There's no claim that God is required to create, but if he does, and if he creates free will beings, and if he wishes to save the maximum number of people (as Craig insists), he is restricted to actualizing worlds in which their is suffering and evil on account of the free will of the creatures.
Wes Widner also states: "It is disingenuous to claim that Molinism is a philosophy whereas causal determinism isn't."
That's a mischaracterization of the situation. Molinism is merely philosophical. Causal determinism oozes from Scripture. It is provable from Scripture - making it a Biblical, and not merely a philosophical, position. Of course, causal determinism is a metaphysical claim. That's not the issue.
Wed Widner futher states: "You misrepresent Molinism as a doctrine wholly based on the freedom of man's will."
The foundation of Molinism is the novel concept of "middle knowledge." Middle knowledge is defined based on the actions of "free" creatures, especially men. So, to deny that Molinism is a doctrine wholly based on the freedom of man's will is only a plausible comment if one is using the terms "wholly" or "man" in a way that is stronger than anything the critics of Molinism would intend. As such, the assertion of misrepresentation is unfounded.
I'll limit my comments to those points in view of Steve's fuller discussion.