This was one of the very first SF books that not only got me over a horrible breakup, but also opened my eyes to the possibility of worlds that exist beyond swords, dragons and magic. Titan is weird, to say the least, and the general ability that Varley has to write eerily real text that effortlessly bends genders and kicks out the legs of conformity likely spurred my own interest with those genderbending immortals of the fantasy setting, the fey. Basically a late 1970s-style space opera - they sure don't make 'em like they used to!
Without getting too much into Spoilertoria, this basically takes place in a plausible near-future until something is discovered in the outer orbit of our solar system. Something big.
And while much of the treatment of sexuality and social mores will likely seem dated to us writing in the twenty-first century, keep in mind that this was written over three decades ago, and was pushing a lot of boundaries when it first came out. It won a Hugo, after all. Definitely recommend this to anyone who is looking for something outside of the usual, from a surprisingly fresh perspective.