This is kind of the definitive work in the subject, so far as I understand. I imagine there is variance -- 70 million people rely on him being a liar. I don't notice any bias 200 pages in. He does say that it was a calculated genocide, though, and it was consciously implemented by the Young Turks, Ataturk included. That's pretty damning stuff.
Akcam is not Armenian, himself. He's Turkish, in exile.
I'd really recommend it. Any discussion on the subject from here forward will pertain to this book.