Let's start with the positive things that Abraham does. In chapter 14 Lot get's captured and Abraham saves him. That was pretty cool. In chapter 18 Abraham tries to help the people of Sodom by arguing with God on their behalf. Pretty cool move, although it does seem to go against the idea that he was obedient and trusting in God. As far as I can tell, these are really the only things that he does that I would put in the good column.
As far as negative things, let's start with the first significant thing we see Abraham do. In chapter 12 when he is afraid he will be killed for his wife's beauty, he responds by claiming she is his sister instead of his wife. This cowardly act resulted in his wife being taken as some other man's wife. Furthermore, at the end of the story the Pharoah returned Sarah and was just pissed that he was lied to. We see at this point that Abraham is not only a coward, but a horrible judge of character. For some reason, Abraham tells this same lie in chapter 20.
Throughout these stories, God promises them they will have a son over and over again, and yet Abraham goes ahead and has a baby with Sarah's maidservant Hagar in chapter 16. It would seem that Abraham's trust in God isn't really that great. In chapter 21 God finally comes through and gives Abraham and Sarah a baby, and they kick Hagar out on her own. Really a screwed up move.
some reason is held in high regard by the religious. They will say it is good that Abraham was obedient, and that he trusted God. I have two responses to that. First, if we look at the rest of the stories involving Abraham, we can see that he doesn't seem to trust God all that much, and he wasn't always completely obedient. But more importantly, when someone tells you to kill your child, it is a bad thing to be obedient to them.
Finally in chapter 25, Abraham remarries but he has a bunch more kids. He treats Isaac much better than the rest of his kids, which I must say I am not a fan of at all.
Honestly, I keep asking myself if I'm being too hard on the things I read in the bible, and I really don't think I am. Take these stories and tell them to someone who has never heard them before and how do you think they would react? Would they consider Abraham a good guy or a bad guy? I'm guessing pretty much everyone would think he is a piece of shit. Why would you consider him a hero? Why would you want to follow his God?