Stick to the books!
If anyone wants to make a good Alex Cross movie (or tv series) then stick to the books! James Patterson is an incredible story teller. If you've read anything he's written you can see the characters, you get to know them. This could have been any detective; the movie did not do justice to James Patterson.
Why did they move the story to Detroit? Why did they make his partner white? Why didn't they have a more imposing actor? Idris Elba has been mentioned. With Tyler Perry as Alex, Elba would have made a great John Sampson!