Is Severus Snape good or bad? Why do you think so?

I personally think he is good. Yeah, yeah, he did kill Dumbledore, but I still think he didn't want to do it. He made an Unbreakable Vow with Narcissa to help Draco with his task or to DO IT HIMSELF if Draco failed. I think he was working undercover for Dumbledore, and wanted to know what Draco was doing. It's obvious in that conversation that he's bluffing about how much information Voldemort has given him. He made the Vow not knowing that Draco's mission was to kill Dumbledore. So then he had to kill him since Draco did not. Dumbledore has a horcrux. The evil thing about horcruxes is the fact that you must kill someone. And yes, he HAS killed someone. Remember his Chocolate Frog card where they found out about Nicholas Flamel? It says right there "and his defeat of the dark wizard Grindelwald" which means that Dumbedore was probably forced to kill Grindelwald to stop him, so he wasn't being evil. Being recorseful, he would have used this to make a Horcrux. Fawkes anyone?