Well, there are like 4 storylines going on at once, and above you mentioned that you couldn't keep the characters straight. I imagine, then, that you weren't invested in any of the characters and simply didn't care what happened. I suppose that is the risk with carrying too many stories at the same time. Maybe you tried to read it whilst being distracted? I tried to listen to GotM as an audiobook and found that it was too easy to miss important information, same thing with DG. I picked up the book and focused on it and found it much more enjoyable.
I don't think you did anything wrong

as long as you formed your opinion by reading the book and not just basing it on what a review said, then there is no reason to invalidate your opinion.
I'm only about 25% of the way through DG, and really enjoying it. Maybe it gets boring later and I just haven't gotten to that point yet.