To begin with, from ch 1, why does God feel like he has something to prove to Satan? God first tries to show off with Job because he's such an upstanding citizen. Satan suggests that's only because God spoils him. Then, to prove Satan wrong, God gives him permission to mess up Job's life.
Why does God feel the need to one-up Satan? Suggests insecurity to me. I would think the almighty God of the universe would just say, "Who cares what you think. Nobody invited you here anyway. Now bugger off." Doesn't make God look very good to me.
The next disturbing thing is that this story suggests God gives Satan, and presumably other fallen angels (demons), permission to screw with our lives - destroy our property, kill people we love, give us disease, etc. I guess God can do what he wants, but it kinda sucks for us. Especially because Satan is invisible to us and we can't even see that it was him that did it. Job never knew it was Satan that did all this stuff to him. Indeed, Job and his friends spend a tedious amount of the book wondering back and forth what he did to deserve the misery he was in. So we're just left wondering if it was God directly, random chance, bad luck, consequence of sin, or maybe interference by invisible evil gremlins.
Then there's the whole issue of God treating Job like a lab rat. "Hmm, let's see what happens to a good person if we torture him to the point of death." Again, I guess God can do whatever he wants, but again it doesn't make him look good. And while God didn't do all of these awful things to Job directly, he knew what Satan was going to do and he allowed it. The story implies that Satan wasn't allowed to do bad things to Job until God gave him the go-ahead. So to me it's just as if God hurt Job himself.
Whether the story of Job is literally true or just an allegory, it's included in the canon of the Bible to make a point. I just don't think it makes a good one.
I realize I'm very cynical. I'd love to hear some positive spin on this book if you've got it.