hmm...tough question...
DS1: Parenting was about what I expected. Actually, it was a bit easier. I hated having to go to work, as I'd intended to stay home. I had marital issues, which made things difficult in other ways, but parenting was a snap. It all just came so naturally. I remember the Home Health Nurse assuming that I must have done a "ton" of babysitting, and I really hadn't done any...
DD: I waited 10 years for dd...fertility issues, and 3 m/c. I wanted her so badly. And...it was hard. She was colicky, and I was having issues over having another c-section and my recovery was painful. She cried for 3, sometimes 4, hours every night for the first few months. It was absolutely brutal, and nothing that came naturally to me worked. She didn't want to be rocked, nurses, sung to, cuddled - nothing.
DS2: It got easy again. My instincts were all on track for him - lots of love and cuddles and songs, and he was happy. He's become a little more difficult since, though.
Overall, things aren't going quite like I expected, but that's mixed up with a lot of other stuff. DS1's dad and I split up when ds1 was 7. I never expected to have all my children by c-section. I never expected to lose 4 of them. I never expected to be experiencing "young couple starting out" finances when I was 40 and had a teenager (this is a hangover from my first marriage).
Honestly, my biggest challenge has been trying to find the patience to deal with kids when I need alone time to process my own emotional crap. I never expected to be trying to cope with active, curious, demanding children, while grieving a death, for instance. Children need so much from us, and it's hard to provide that when you're not even sure you have enough for yourself. That's been the biggest con (that and a ton of never fully resolved birth trauma).
Pros? TONS.
Feeling a baby fall asleep against me at night. Breastfeeding, once it gets going (I tend to have some trouble in the early days). Having a 3, 4, 6 or 10 year old spontaneously say, "I love you, mom(my)" and give me a hug. Having my kids ask me to sing to them at bedtime, because that's become so important to them. Watching them figure out the world around them, and put all the pieces together. Having another parent or a teacher seek me out and say, "you're [ds1]'s mom, right? He's such a great kid - I really enjoy having him in my class/over to visit". Having my son encourage me to join a choir when I was nervous. Realizing that, even though I've never had any self-confidence to speak of, I've managed to gift my son with a ton of it. Seeing my oldest snuggle up to his siblings, so that they'll take a nap. Asking dh what he thinks of my new two-piece swimsuit, even though it doesn't look that great (I bought it so I could swim during this last little bit of pregnancy, as my usual suit won't go over my belly)...and having ds2 say, "you look beautiful, mommy". And, realizing that they really believe I'm beautiful, no matter what. Knowing that they trust me, absolutely - always. It's all just...amazing.