Depending on who you talk to, Singleton as director is a big concern.
 
 
 
Tyrese cannot pull off a comic book style Cage. He has been in roles that require him to have a tough guy vibe at times in Baby Boy and 2 Fast 2 Furious and failed to inject that into the character. He is better off as a comedic character, b/c that is honestly closer to who he is. I don't think the roles in those two films are remotely close to who Tyrese is. He's not a wannabe hardass like Jody, he's not a street kid like Roman, and the fact that I couldn't get into those characters and could only see Tyrese is his fault, he did nothing to bring those characters to life. The light hearted moments in those films are where Tyrese shines, and Luke Cage is a hard-nosed character. Cage's bravado is an act to a degree, but is is hard guy, and if the films fals to nail that, it won't be very true to the character. 
 
I will agree, however, that the biggest area for failure is the script, especially considering it was written by Ben Ramsey (The Big Hit, Love and a Bullet) who has a penchant for fusing comdey and action, but does not always have the knack for pacing, which is also Singleton's weakness as a director.