He actually managed to save everyone and did not mention it, he kept putting himself in mortal danger for the life of a boy he didn't even like but to protect him, because Harry was the person Lily cared about most in the world, and Lily was the person Snape cared about most in the world.
So what do I think of him?
I think he's easily the bravest man on the Harry Potter saga. Not the kindest, not the most handsome, not remotely charming. But he was the bravest and pretty smart too.
He's the catalyst to the entire story, it was Snape who told Voldemort about the prophecy who set everything up (the Potters going into hiding, Voldy choosing one kid) and it was Snape who let Harry knew what must happen at the end. (When he gave Harry his memories it was so Harry could understand what had to be done)