I didn't like it because it was long.

Very long.

Very long and full of characters that don't do anything.

Very long and full of characters whose destinies are writ in stone.

I don't like it because nothing happens, and then when it does, it's completely unearned. One semi-spoilerific example:

Lives are saved in this book. Which lives? Why? To what end? Do they matter? Does that matter? NOT THE POINT - the fact of the matter is, our access character's entire life revolves around the ultimate point in this book, and he doesn't give a fuck.

Here's this ultimate angel, this reviser of futures, this "miracle" and why is he the way he is? Because he's miraculous. Okay. But what miracle is he performing? He's saving lives. Okay. Why those lives? Why then? Why there? Why that way? WHY? See, that's a mystery that neither the access character nor the author care about. And what part, in this ultimate miracle, requires him to strike a baseball with such force? The other locus of the book - the one at the beginning that sets events in motion - is completely irrelevant to all that follows. We're dragged through 600 pages to end up at our destination but the fundamentally life-changing event that launches us in that direction? Never plays. Is never relevant. Serves no goal whatsoever.

In It a fundamental tension is put in place that changes the protagonists forever. In order to complete their hero's journey they must solve that fundamental tension. In Owen Meany it comes about as an "oh by the way" moment.

Finding traces of other books isn't a big deal - good artists borrow, great artists steal. It's when the traces that are borrowed are so much better than the material they end up in that I hate it.