Written around 335 BC, this work can be regarded as the first ever to handle literary criticism. The philosopher, with an incredible erudition and drawing from a rich variety of authors who are now part of the canon of Ancient Greece's literature, lays the foundation for textual analysis that is still relevant to some extent today.
Now, it is true that he lectures the reader without being engaging, and the number of authors he quotes might be overwhelming for those who are not familiar with most of their work (as I admit I am). Therefore, it can seem boring and pompous. However, his thoughts and arguments can be followed quite easily.
Starting from the question of what poetry is, he proceeds to detail the different genres that define it, mainly tragedy and comedy. Unfortunately, we can only read about tragedy as the parts about comedy have long been lost. He actually dissects various works, showing the importance of plot, characterisation, the language being used, the thoughts being expressed, and even staging effects - which are in the background but still play a role, albeit a minor one. It is interesting to see him analysing such art, from the texts themselves (style, metaphors, the role of the narrator, etc.) to a more global approach (Greek poetry being a performing art: music, songs, and the effects produced on the audience). Thus, he indeed provides a very precise idea of what poetical creation is while also pointing to tools to better analyse and criticise it.
Although it is a short read that one can breeze through, just picking the relevant tidbits as one goes along, this is a classic that should not be missed.