I intend to read some more of his oeuvre, starting with En Rade (available from Dedalus); he was also a formidable art critic. His most famous work is A Rebours, translated as Against the Grain or Against Nature, a remarkable book, totally without a plot, consisting of a series of erudite heightened descriptions of the methods used by a wealthy aesthete to cut himself off from consensus reality - you will either love it or hate it - I had trouble getting through the whole thing last time I read it, although I think it is highly relevant in the age of 'virtual reality' and estrangement from the natural world. Arthur Symons called it 'the breviary of the Decadence' and it appears anonymously in Wilde's The Picture of Dorian Gray. After having written it Huysmans was told by his friend Barbey D'Aurevilly that he would have to choose 'between the barrel of a revolver or the foot of the cross' - he chose the latter course, as his later novels testify.
There's a very comprehensive site on Huysmans here.