I have some questions, would you please answer them?

Art Spiegelman wrote Maus I & II using the materials taken from his father, Vladek's, interviews, but after I finished reading Maus I & II, I have a vague feeling that Spiegelman doesn't appreciate his father for his life story. I know that sometimes children doesn't know what their parents had to go through in order to reach where they are now and I feel that Spiegelman is the same way. Does Spiegelman really believe that the story is worthwhile to write even though the only reason the estrangement between Spiegelman and his father ended to the write the story? With Jing's post, she wondered why Spiegelman portrayed his father as a such cold and mean man and I wonder about the same thing. Maus I & II portrayed a man who was resourceful and hopeful until the end, so how did Vladek end up to be so bitter after Anja killed herself? If the way that Spiegelman portrayed his father is true to the last fact, then do you think that Vladek should be this bitter since he survived through the Holocaust a lot easier than many Jews?