Well, depends, some times it works and some other it doesn't, but in theory the role of an actor is to become the character, rather than being "himself" in a different role.
Take Gary Oldman for example, he's been Dracula, he's been Churchill, he's been the bad guy, he's been a police officer in a town where a rich guy dresses like a bat.... he's played so many different roles, Ryan Renolds just look like Ryan Renolds all the time (or most of it).
It's not even a dis at Ryan, there are so many actors being typecast, or that seem to play the same character everywhere, it's not a bad thing per se, but once you notice it, you can't really un-notice it.
Case in point: I don't even remember the name of Ryan's character in the movie, while - first example that comes to mind - when I see Dr. Strange I see Dr. Strange and when I see BBC's Sherlock Holmes I see (a) Sherlock Holmes, and not Benny Cumberbatch in both cases.
Another example, I've seen Jim parsons being Sheldon Cooper in 674 episodes of The Big Bang Theory, and yet in Hollywood he was able to pass off as someone else, playing a different character. It's always nice to see an actor becomes a character rather than remembering him from other movies.