What do you mean by 'natural' piece of writing?
I'm only on page 30 or something so far though; maybe it'd get better.
A natural piece of writing fits one's style, and consequently is flows a bit more readily. I mean, an unnatural piece of writing isn't necessarily a poor piece of writing, but can be a bit broken up, and it's easier for the reader to disconnect with the content.
I'm sure it will get better. Most novels start slowly and build, even those of less fast-paced genres such as the one you're reading.
What's wrong with children's books? I'm still a child, or at least I consider myself a child. So I read novels for ages younger than me, for my age group and beyond my age group. It's irrelevant, though and doesn't influence my enjoyment and pleasure.