There are later books than this one that are given as candidates for the first novel, but why anyone would not think that this book is not a novel I can't imagine. It is essentially a picaresque with the main character being turned into an ass and then propelled from one humorously perilous situation to the next. It reminds me a little of Don Quixote in that their is a central ridiculous but loveable character, but Lucius is much more a passive actor who is propelled by the fates than Don Quixote.
The book is well worth reading. It is very roman in spirit and a moral work, but its morality is a strange one. For instance, its most powerful moral message is don't be curious because this inevitably leads to disaster.
It is filled with people behaving absolutely appallingly and has a large number of murders which are done usually for humorous effect. A good book. Well done and well worth reading.
The donkey sex scene is tastefully done.