Great idea, sloppy execution.
Past the quarter-mark, I couldn't shake off the impression that it was lazily written. Each chapter opens with a bit of relevant infodump that is most often third-person omniscient or once, even, POV-switch, and then we go back to the story in first-person. Other characters were intriguing, but they bent any way the winds of plot blow. Yes, when in first person limited, there should be slight unreliability, but I daresay inconsistencies here cross the line. A few "late reveals" don't really feel set up well. That gun should have been seen lying around instead of suddenly materialising in hand, cocked.
Writers, beware: first person might seem like such an easy way out, but there will always be some nitpicky hair-splitter to nose out the misses. I didn't really mind it otherwise, though there is one small problem Rameau mentioned in her review - magic doesn't sound convincing enough.
And not just magic - while Fitz does get his periods of woe, there are very few lingeing consequences. He's surprisingly articulate once he got over his wariness for a boy who was barely taken care of until the age of six, and then raised by dogs and a man who treated him as another animal to groom. Neglected as he was, why didn't he already form union with an animal, prior to coming to the stables, and slipped halfway into a beast's mindset? It would have made perfect sense.
Also, for all that the title says "Assasin's Apprentice", that element is barely there. While I can appreciate a book being complex, in this case it's simply misleading. Particularly since the setup was ideal for the opposite kind of story - a boy with no name and known relations, more kin to dogs than humans - perfect for assasin-in-training. But he resembles the King-In-Waiting to a surprising degree...Yes, it's cliched, but the book isn't quite brimming with originality anyway.
That's not to say there are no good things. It's exactly because there was so much that was interesting that I'm disappointed. I expected much more from an author this much lauded.