The idea of listening to a porcupine's confessions to a baobab is amusing and light-hearted but his story raises the most serious cultural and ethical issues. I'm reminded of nothing so much as Hannah Arendt's Banality of Evil, with digressions on the relationship between evil, power and the possibility of redemption.
This is not the first time I've read a fable written from the point of view of an animal and most of the other recent ones come from outside the English-speaking world as well. They've almost always been ways of raising quite complicated philosophical issues in an approachable way and of commenting on human society from the outside. They come across cute and easy to read, but they are meant to be taken to quite a deep level. It works for me. I will probably read this one again soon so I can think a bit more about some aspects of it.
With respect to the porcupine's talkative style and digressions: considering some of the sentences are several pages long, it's amazing how easy this is to read and follow. You're just going to have to trust the porcupine on this one - it really works as advertised. It's just like listening to someone talk (only well).
Last point: the translator, Helen Stevenson, has done a great job reproducing a colloquial feel. I found this book by chance in my local library and I hope to compare it with Mabanckou's original sometime soon.