Aha, I've had little ones from my siblings since I was five, and I'm currently an uncle of four nieces and three nephews. :P
To be honest, the idea of having children myself sounds like an overwhelming responsibility, but I do cherish my siblings' kids, and (hopefully) they cherish me as well. I see them often, and play with them when I have the chance, but sometimes I'm just not feeling it and tell them that I'll play with them later. They're all very diverse personalities, and are genuinely nice kids with charming curiosities although they do mess up sometimes, but its to be expected. I like listening to them, but I am guilty of faking attention, which I shouldn't do but my laziness can get the best of me quite often unfortunately.
Overall, its a learning experience to spend time with such bright, passionate and hyper kids, but they're well worth it. I love every single one of them. :) But, this is just my experience, and children are not for everyone. Its important to remember though that they aren't little machines or aliens, they're just small and limited human beings that are growing into their potential, and deserve to be treated with respect, kindness, and empathy that they need.