|One of the best fan-posters I've seen|
Sure I could talk about how 'this actress doesn't look like such and such' of how they have the wrong eye or hair could but this would be wrong. We shouldn't judge an actor simply on whether they look the part. For one thing, it's incredible how much an actor can change physically before starting filming. Just take a look at how much weight Anne Hathaway lost before Les Miserables or the difference between Tom Hardy before and after Bane. An actor you thought looked wrong for a part could surprise you and end up as the perfect embodiment of how you imagined a character.
But more importantly we should base whether an actor is appropriate on their acting ability. An actor could look exactly how you see a certain character, but ultimately if they can't act the role they won't work in the film. It's incredibly superficial to say that you don't like a character just because of their looks and doesn't make sense. Sure, you may want Finnick to be an Adonis but if you dig deeper into his character he is so much more than 'just a pretty face'.
I'm not saying how a character looks isn't important, simply that wait until you've seen the actor in action before judging. Or at the very least a photo of them in character.