I don't understand why everyone's biggest complaint is how "old" been looks. I teach high school kids... he might looker "older" but he definitely fits in with that awkward acting and looking high school kid. And to me didn't stick out around the rest of the main cast and extras.
Also if you look at any other movie or show that deals with actors playing high school roles, they always seem not to fit. Older movies, Grease... 90's movies, she's all that... 2000's, varsity blues... tv shows like 90210 or saved by the bell... I could go on, yet everyone is attacking this and have probably never even seen the Broadway.
I'd rather sacrifice a little age for a good performance and Ben is going to kill it in the acting/vocals.
Don't get me wrong tho, the buzz feed article had some pretty funny tweet compilation of everyone talking about age. I think the movies gonna be great. The only thing I think it will miss the mark on is how the stage show capitalizes on how social media really drives the message forward.