This is the first book in the twenty novel Rougon-Macquart series. Each novel essentially stands on its own and can be read in isolation to the others in the series. However the characters all belong to a single family and they mostly take place during Louis-Napoleon's Second Empire (1852-1870).
'The Fortune of the Rougons' is the tenth book that I have read in the series and it is one of the best of them - mind you, I haven't come across a bad one yet. What makes it stand out from the others that I have read so far is that the period it covers is much longer. It essentially spans the period from around the times of the Napoleonic wars to the beginning of the Second Empire (1852).
Having read more of the later novels in the series I am familiar with several of the characters (e.g. Lisa, Gervaise and Jean Macquart, the Lantiers) and was aware of course that they were related and that some appeared briefly in other novels of the series. But I hadn't paid too much attention to how the novels and the characters were connected. Reading this, the first book of the series, after reading nine of the others, is what made it more interesting than it would otherwise have been if I'd read it first. This way it's like finding out about the ancestors of people I know or like finding out the 'origins' of a character or superhero in a comic.
Reading 'The Fortune of the Rougons' has also introduced me to many of the characters that appear in the earlier novels of the series, making me eager to continue reading these as well as the more popular ones. I'm now looking forward to reading about Eugène Rougon, Aristide Rougon and Serge Mouret in some of Zola's lesser known works.
If you've read any of the books in the series make sure you read this one as well. It really helps you understand the series as a whole, though as usual it can be read on its own. It's well written as you'd expect from Zola and the translation is perfect.