Where to start, where to start... Unless you're a gold-digger who struck it rich or a child-of-the-90s who thinks
divorce is the obvious thing to do when you get
bored, there are so many
sucky things about divorce even if you don't get into all the
legal annoyances (if you're immature enough to go whining to
court over who owns what and who owes who
money):
Figuring out who gets what -- shallow, yes, but it's the classic. Even if you don't fight, you wouldn't believe how much stuff you were attached to until you realize that it belonged to them, not you. Say bye-bye to videos, music, books, appliances, and other things that you never thought you'd have to do without. Months later you'll be thinking "Say, I'm really in the mood for (fill in the blank music) -- oh hell, he/she got that CD!" On the bright side, though, you can probably unload some stuff you didn't want. ;)
Losing good inlaws -- if you were lucky enough to have 'em in the first place. More people get along with their spouse's family than you think, and it's like losing your friends (or worse). You know they have to side with their son/daughter; that's the way life goes, but you wish they'd hear you out too, except that it's none of their business and you don't want to sound like you're the evil ex badmouthing their darling kid, and oh damn, it's all messy. Speaking of which...
Losing his/her friends -- if you were lucky enough to have been good pals with 'em. Even if the divorce was amicable and the friends fairly intelligent, nothing freaks folks out more than hangin' with a friend's ex. There will always be a lingering desire to assign blame, and unless your spouse was a total monster it's likely that his/her loyal friends will feel compelled to blame YOU.
Throwing out the baby names -- okay, it's silly, but let's face it: who hasn't discussed what they're going to name the kids? If you're really unlucky, you'll have settled firmly on the "perfect" names...and now you have to dump them in the trash. Come on. Could you really give that name, a very personal decision for a couple unless one half of the team was a total control freak, to a child by another? That's just creepy.
Being treated like a child by the legal system -- the government doesn't want you to dissolve your marriage because it means more paperwork. So how do they solve it? By heaping paperwork on you until you collapse, and arguing every step of the way as if you're not old enough to make up your mind about such a serious decision. o.O I don't know about other states/countries, but in California you are legally forced to call yourselves "separated" for six months -- only then are you allowed to say you're divorced. As if you might suddenly change your mind or something.
Regaining your maiden name -- this one's just for the ladies. Trust me: it's a pain. Again, the state obviously does not like divorcees, as they make getting your own name back ten times harder than changing your name via marriage. It doesn't just spontaneously happen; you have to do more legwork than Sherlock Holmes and run in more frustrating circles than a champion greyhound. This one hurdle alone will make you never want to get married again.
Feeling like a failure -- again, unless you regard marriage as a disposable commodity (and, sadly, people do), you feel like a loser. When you got into the marriage you knew, absolutely knew This Is The One -- this is the person with whom you're going have kids and grow old. "Look at me, world! Look at me, family! I'm all grown-up! Yay!" Now you slink around unable to look anyone in the face, especially if they were at the wedding. You wonder what they see -- a child playing at being an adult? An irresponsible flake who was only in it for the gifts and attention? A typical example of "that generation"? Ugh.
Wondering about the next relationship -- IMHO, this is the worst, and what I intended to write in the first place, but everything else wanted to be said too. The worst thing about divorce is that it shakes your belief in love and in your own judgment. It's far worse than merely breaking up with a girl/boyfriend. Marriage is supposed to be IT...and it wasn't. The next time you fall for someone you remember how madly in love you thought you were with "the last one," and how wrong you were, and how long it took for you to find out how wrong you were.
Doubting your own emotional competance -- again, a pitfall of the next relationship, and probably the reason why divorcees are often stereotyped as flighty. You start to think in vicious little circles: is this really love? You thought it was last time -- you really did. Maybe you just think you're in love, or you're just in love with being loved. The person who's now in love with you, will they stay once they get to know the real you? The last person ran screaming, after all. Is it fair to him/her to put them through what you've just gone through, in the end? Is it real? In relationships, what's real? What lasts? How do you now this is The One? You thought the last one was The One and look how that went, you idiot... And so on. It's ugly and more than a bit pathetic.
I'll stop there before this becomes a whinefest -- that covers most of the basics, I believe. I know there's a whole other dimension of pain involved when there are children in the marriage. If someone else would like to cover that angle, I'd be much obliged.