What I have found is that babies vary a LOT in difficulty. All will require being inconvenienced. Some are easy. Some will put you at the breaking point crying for hours on end. The strain it puts on your life varies wildly.
So take all advice with a grain of salt. People will say that it's all fun/rewarding with just some inconvenience. Others will say that it sucks bad, and that anyone saying otherwise is a liar. Neither is wrong as that may very well have been their experience, but don't let that shape your expectations.
People also tend to only talk about the positives and that creates false expectations and disillusionment. "Oh, you're having a baby! It's such an amazing experience, you'll love it". That's all we heard. Our baby turned out to be a very difficult one. Only then, when we sought advice about how to cope, did those same people admit that many times in the first few months it's not much fun at all.
Most people only talk about the positives because they've seen the fruits of their labor. They think of the things kids do at older than 2-3 months (See post by shhh.... and others here). But at first all you do is take care of something that can't yet reciprocate any kind of connection, not even a smile. It's hard for a first time parent with a particularly difficult baby to see the light at the end of the tunnel in those beginning months. It's a short period though, so it's manageable, even if it doesn't seem like it at the time.
So everyone bashing people admitting that it sucked for them, don't be so quick to judge. 1) they are most likely only talking about the very beginning stages, and 2) their experience might be vastly different than yours.
The universal opinion though is that it is wort it and highly rewarding in the end.