It is extremely scary because you don't know what to expect. Especially since you speak to other moms who say "Being a mom is soo hard" or "Your life will completely change once you've had a baby". Which it does, I'm not going to lie. I didn't realize how much my life would change until he was actually born though.
The newborn days were extremely difficult for me. 24/7 with a baby on my boob, can't go in the shower because if I lay him down he will scream, can't pee because if I lay him down he will scream, etc. Toddlerhood has been interesting, especially when we're shopping and he's screaming his head off around the supermarket. LOL makes me really wish sometimes that he was still a newborn baby who likes being pushed in a stroller.
One of the biggest adjustments for me was not having time to myself anymore. I really get none, unless he's asleep but then I'm usually cleaning up the house and by the time I sit down to watch TV, he wakes up and wants to play. Sleep was a big adjustment too, be prepared to get little to none for the first few months (or 16 months in my case).
I absolutely love my son. I really wouldn't change having him for the world. Your life changes but in a good way. One of my favorite things about being a parent is watching him grow, learn new words, etc. It's just fabulous. You will love it too but it's normal to be scared. I am scared too about him growing up! I wish he could stay 2 forever (no, I don't.. terrible twos!)