It's annoying isn't it? I specifically hated people saying how 'hard' it was but not explaining why. I knew our life would change & we were really ready for that but tell me what aspects are the hardest. No sleep is a big one & people just say it like you'll be awake 24/7. I love my sleep but I coped really well, my partner helped loads & I got between 3-6 hour stretches whilst he took over (I expressed or we gave formula, EBF could be more difficult to get a block). By 9 months he slept through.
However the 'hard bits for me if people ask are...
Having to constantly plan for another person, what they will wear today, eat, drink meaning I always have to be on top of food shopping, packing the baby bag, it's no longer a case of up & out.
Not being able to leave them unsupervised whilst you nip to the loo because once you return, they've scaled the coffee table.
Keeping on top of the housework. We try our best but it's not easy as DS won't just sit & watch, he'll be trying to eat the cillit bang or attempting to get in the washer. We aim to do jobs when we are both home or have family help which is often so we are lucky but I have lowered my standards
On a positive note, we are the lucky ones that get to eat together every evening at 7ish & this has only ever been affected once that I remember as DS slept lots as a newborn & goes to bed at 7pm now (lots will tell you that you can never eat at all/never eat as a family/Will have to eat at 10pm - I proved this isn't always the case)
Good luck, it's literally wonderful being a parent & one person's 'hard' is not necessarily the same for another person's