A wonderful book in a genre I don't normally read! 
 Mattie Ross is a great narrator, and seeing the story strictly from HER point of view really adds something the movies don't have. You get extra details a film can't logically slow down to show you without it feeling crammed in but which fit perfectly in the first person prose. 
 Its a rich and engaging story with an almost alarmingly simplistic plot (girl's dad gets offed, girl is ticked and wants his murder offed; hires one eyed fat guy to capture him, complications ensue... That's pretty much it in a nutshell), saved by engaging and remarkably deep characteriaztion. 
 If like me you were told the book is most similar to the newer film you were probably lied to. The 2010 film is more true to how the characters would've looked, talked, and reacted but strictly in terms of plot faithfulness (all except the ending) the John Wayne movie is closer to what you're getting here. 
 Favorites and highly recommended!