Mainly because I've invested so much of my time into it that I feel like I should finish. It's only okay. I'm listening to it on 1.5 speed to make it go faster.
It is always slow, but there are spurts where it gets interesting, and then falls back into the slow pacing. I'd give it a solid B-.
My biggest critiques with it are the overuse of similes--many of which make no sense.
Also, I don't think that the main character is that interesting. He puts himself on such a high pedestal in the story, with so many amazing powers and far fetched experiences that it is totally boring.