Critical opinion states that Curtis combines terrifying historic events with "honest" characterization so that Kenny's and Byron's reactions are truthful without the exploitation of excessive drama and horror. The dialect Curtis employs is thought to add a realistic and appealing flavor to the dialogue. Thus it is both interesting and believable.
The use of Southern black dialect in Momma is realistic, and the allusion to the Sixteenth Street Baptist Church bombing in Birmingham, Alabama, lends verisimilitude to this novel. The narrative is interesting to junior high school students and provides them the perspective of how conditions differed for blacks from the North as compared to those in the South.
You might receive a range of different views on this question, but I certainly believe that this novel is interesting and believable. I think in particular the portrayal of Kenny and the way that he struggles in so many ways in his world, with bullying and then with the violence that he witnesses in Birmingham, adds a definite note of realism to this excellent text. Just to give you one example, note the way that Kenny struggles to make sense of what he witnessed in the final chapter when Byron gives him a good talking to:
"But Byron, it's just not fair. What about those other kids, you know they had brothers and sisters and mommas and daddies who loved them just as much as we love Joey, how come no one came and got them out of that church? How's it fair? How come their relatives couldn't come and warn them?"
We see Kenny realistically struggling with some of the big issues of life and not finding any easy answers. Here he is trying to make sense of why life is not fair, and how this fits in to how he looks at the world. Such struggles that we share with Kenny through the first person point of view are excellently conceived and definitely make the novel interesting and realistic.