Fans often get upset because what is depicted on the screen isn't exactly 100% to the comics. But they need to understand that some elements don't translate well. So long as they capture the personality, mannerisms, look and general spirit of the characters they are adapting - and treat them with the respect and reverence they deserve - it is all good. For the most part, Marvel have adhered to that aspect (the few missteps being Mandarin, Zemo and the Ancient One.)