I wasn't too interested in Franklin's character based on the trailers but to my surprise he was perhaps the most likeable of the bunch. I also liked the setup of him trying to get out of ghetto while pretty much everyone he knew from there was critical of his path and wondered if Franklin had forgotten his "roots".
However when Franklin was talking with Lamar there were so many, niggas, bros, homies and motherf*ckers thrown around that it just felt ridiculous. A real shame. I could not imagine watching The Wire if the black characters spoke like that. It would be just as ridiculous. Granted, I'm sure there are fellows who go around speaking like that but maybe, just for the sake of not drawing attention to the way they spoke, Franklin and Lamar's dialogue could have been toned down a notch on the "nigga/motherf*cker" department.
F*cks were flying pretty often for Michael and Trevor too but maybe just a little bit too much. It didn't take away from the moment very often.
And for absolute clarity let's be clear: I have no problem with cursing or any words. It's just that dialogue needs to sound natural, not forced. Perfect example, The Sopranos (or The Wire). There's a ton of cursing in both but it never feels out of place.