Lucan was the nephew of Seneca the Younger (one-time tutor to Nero and forced by him to commit suicide) and so he has a very personal response to hereditary monarchy which comes over very clearly in this text. Re-telling the story of the civil war waged between Julius Caesar and Pompey, he also explores the re-establishment of monarchy vs. the supposed independence of the republic.
This is a very literary text and relies on the reader's knowledge of other Roman epics especially Virgil's Aeneid, but also Ovid's Metamorphoses which itself challenged what the epic genre could and should encompass. But it's not strictly essential to have a knowledge of either Roman literature or even history to enjoy this book though it undoubtedly helps in terms of exploring the nuances.
Braund's translation (OUP Oxford World Classics 1992) of the Latin poetry is in free verse, and is flowing and powerful. Her notes and especially introduction are excellent contextualising the poem in many directions.
I have to admit that this isn't one of my favourite Latin texts but Lucan's sensational episodes are very gothic and almost worth reading in themselves, replete as they are with bloody portents, witches, and all manner of gore. Caesar's affair with Cleopatra is also extremely lurid but it's a shame that the text breaks off at that point as Lucan never finished the poem. So worth a read but not a good introduction to Latin literature.