1. The sleep deprivation both is and isn't as bad as you hear. Yes, you will go crazy. Waking up every 1-2 hours for weeks -- months -- on end? There are no words to describe how it will eat away at your ability to function. You will be crabby and short tempered and you may just find the mayonaise in the dishwasher and the forks in the fridge door more frequently than you care to admit. But the good news is that you can and will survive (mostly because you have no other choice!)
2. Good sleepers are born, not made. I'll be the first one to admit how wrong I was in my assumptions about baby's sleep habits. Now I get it. You've got to work with the cards you're dealt, and some babies just don't sleep very well. We started off doing everything "right", and one day, Jack simply stopped staying asleep. Of course the parents who happen to have good sleepers are certain of their methods (try convincing them otherwise), but once they happen to give birth to a child who wakes up every 20 minutes or screams bloody murder until you just pick him up and help him settle, they'll change their tune.
3. Babies have incredible personalities from the get-go. You will be astounded to realize how much you can learn about the kind of person they are from when they are so very tiny. They will make you laugh and smile and cry, and even though they will be dependent on you for their physical care, their personality development is all their own.
4. You will be amazed by yourself. Pregnancy. Birth. Lactation. Sleepless nights. Love. Rocking. Soothing. Patting. Singing. Smiling. Giggling. My oh my, will you be amazed by yourself. You will discover love and devotion like nothing you ever imagined yourself capable of. You will see these traits in your partner, too, and you will love them more than you ever thought you could.
5. Sometimes you won't be proud of what you feel. Nobody warns you about this part, but it seems to be fairly universal. Just like their are moments in time when you can't stand your spouse, there will be moments in time when you can't stand your baby or yourself. You will wonder what's wrong with the two of you. The situation might feel hopeless. You will be angry and frustrated and full of tears. But it will pass. It will always pass.
6. You will be a junky, and act accordingly. We are all addicts. We are addicted to our babies. Sure, we decided to be parents because we wanted to give life to and care for a tiny being, and this aspect is selfless. But let's admit something here: we are addicted to our babies, in part because of how wonderful they make us feel. We want to hold them and kiss them and smell their hair. They calm us and we can only go so long without. They feel the same way about us (for a while, at least), which is pretty amazing when you think about it.
7. Yes, you will be that parent. You will sniff your kid's butt to see if he needs a diaper change. You will videotape his bodily functions and share them with others. You will wipe away snot/drool/spitup without thinking twice. You will pull pictures out of your pocket at the slightest hint of interest from others. You will tell inane story after inane story. You will love it. You will have no idea how foolish you look. You will be so smitten with your new addition that all else will fade. And you know what? That's just fine. Indulge and enjoy.
8. Yes, you will also be that parent. You will be frazzled. You will martyr yourself at times. You will be so focused on your child that you will lose track of other people and other things. You will be crabby and short tempered. You will be very upset by things that other people won't understand. You will be late and have bad hair. A lot.
9. You might lose a bit of yourself. Who am I kidding? You will lose a lot of yourself. You will forget who you once were. Your life will be so completely different that you don't recognize the new person. And you will miss that former life, no matter how much you enjoy the new one.
10. Your child will be totally perfect. In between teething, growth spurts, mental milestones, regular illness, vaccines, diaper rash, and good old fashioned bad days, your child will be, clearly, 100% perfect. All the other times don't count. And those moments when his or her personality shines through... they will be so spectacularly beautiful that the addiction will be reinforced and you will find yourself musing about when to have another one.
Bonus! 11. If you don't have them already, you will develop masochistic tendencies