If there has always been one constant with discussions about comic book movies when they are in the earlier stages of production, it would have to be the following two things: have they casted the movie with the right actor(s), and second will they get the costumes right?
Almost every time I read about a new comic-based movie being put into production it is not long before I start to see these same two concerns expressed by the fans of the comic property. Even now, with the start of production of two new comic based films, Captain America, a Marvel comic book character, and the Green Lantern, A DC comics character, fans are expressing concerns about who has been cast and what they wil be wearing.
In the case of Captain America, the choice of Chris Evans as the proinciple lead (Captain America/Steve Rogers) was met with a thumbs up by many but there were definitely a few detractors. So far, however, there has not been any increase in fan backlash towards Evans, probably due in part to the fact that he has handled himself well on the recent Summer Marvel movie press junckets he has been a part of.
With the costune, the initial reaction has been mixed; fans were uncertain of how to take the news that the look of the character would be based more on practicality and the more recent look of the Marvel Ultimate line of comics than on the more traditional and familiar look of the hero from the comic. Until some definite footage is released showing us how the costume asctually looks it will be hard for the fans to express any definite opinion.
For the Green Lantern movie, fans were mostly okay with the casting of Ryan Reynolds as Green Lantern/Hal Jordan, even though he had previously portrayed a Marvel Comics character(Deadpool) in the movie X-Men Orugins: Wolverine. Of course Evans got some similar response from fans since he portrayed Johnny Storm in two previous Fantastic four movies.
The look of the costume has been a bit of a negative for many Green Lantern fans: the look that been adopted so far has some designs on it that are not present with the comic book and this has some fans of the comic starting to second guess the visiual design of the movie a little.
So, as you can see, when a comic book character is adapted for the big screen, the fans of the character will always have somthing to grumble about and casting and costumes are always going to be the big two that get most of the heat.