Yes it has been known for a while that The Perks of Being a Wallflower star Ezra Miller will portray The Flash in the DC Cinematic Universe. While yes Ezra Miller is a very talented young actor, he isn't exactly what is universally thought of when you say The Flash. I for one was a big fan of Grant Gustin's portrayal of Barry Allen, I thought he played the role with absolute perfection. It has always bugged me that they went in a different direction in the Cinematic Universe.
He doesn't fit Barry Allen's personality
Barry Allen has always been a real stand up kind of guy. Think of him as the Steve Rodgers of DC. I just don't get that vibe from Ezra Miller. He seems like he should be playing a much darker kind of character. I just can't picture him as being a man amongst men like Barry Allen always has. Ezra Miller to me is definitely more suited for some type of villain, not a leader of the Justice League.
Why not Grant Gustin?
Anyone who has seen The Flash on CW knows that Grant Gustin was absolutely terrific as Barry Allen. After his performance it leaves me wondering why DC didn't just go with Gustin for their Cinematic Universe. I understand their whole plan of keeping the TV and Cinematic Universes separate but in doing that it causes problems like this. Grant Gustin truly embodies what Barry Allen stands for, he is brave and a true Man amongst Men. Grant Gustin is definitely someone I could see leading a team such as the Justice League much like he will in Legends of Tomorrow.
He looks nothing like Barry Allen
Ezra Miller looks nothing like Barry Allen. Grant Gustin doesn't exactly look much like him either but definitely more that Miller. Ezra Miller, for lack of a better word looks sort of like a skater kid. He isn't exactly a clean cut type of individual as Grant Gustin is and I really can't see him as Barry Allen. However, appearance does not judge the actors portrayal of the character, their acting ability is what really matters and Miller is very gifted in that aspect.
Is he Physically fit for The Flash?
The Flash in the comics stands at about 6'0, Ezra Miller stands at around 5'11 so height wise he is right there. When it comes to body type however, he doesn't exactly fit the build for The Flash. The Flash has always been a very muscular character, Ezra Miller very small and lanky. He just does not have the body composition for the role and as of now I can not picture him as The Flash. This can all be changed however, actors constantly bulk up for roles so it is not a stretch to think Ezra Miller could do it.
Is he really the right person for The Flash?
I am one who tends to reserve judgement in regards to castings before I see it in action. Same is true with Ezra Miller, while yes I am very skeptical on the idea of him as Barry Allen I am willing to give it a chance as everyone should. DC seems to be looking to change up the character a bit and it remains to be seen if these changes are for good or worse. I am still a strong supporter of Grant Gustin's Flash but Ezra Miller may surprise me and I hope he can. It definitely wouldn't be the first time I was wrong (Andrew Garfield as Spider-Man). Only time will truly tell if Miller was the right choice, as of now however it will be very difficult to top Grant Gustin's performance.