Certainly an iconoclast biography, though Coleman states in his introduction that it wasn't his intention at the start. Pay attention to that word Legend in the subtitle: that is exactly what the greater part of the book deals with, digging up the sources for the legend and showing where exactly it's been whitewashed, distorted, or just made up from nothing. And it is well-researched, with pages and pages of bibliography and notes.
Another bonus is that it's not required that you have the history of the period at your fingertips (though of course, if you are taking up a book about Nelson, you should know who he was): the author is quite adept at peppering his text with hints about who this or that personage was/was going to become, etc.
I personally, not being British, never had an idealized image of Nelson; I've read the Southey biography, which Coleman calls a hagiography, but even that one made me, in places, suspect something wasn't right: Southey really protested too much. If I remember rightly he'd even supported the "Horatia Thompson" fiction.
Coleman's work certainly looks like a sincere attempt at painting the real man behind the hero (look, I didn't go to check the sources, all right?). The merits and faults of Nelson the commander stem from one source: furious desire to win, both for his country and for himself. The faults of Nelson the man are numerous, as I think most people did already suspect.
There's just one aspect of this comprehensive portrait I have issues with. What of his professional capacity as a captain, not as a leader of the fleet? Surely I've met (in fiction) with lots of practical seamanship ideas, claiming to descend directly from famous Nelson? Of course that could have been just a part of the legend. On the other hand, it might not. That was left completely untouched in this whole book. When commenting on the technical terms about ship, Coleman states he's been trying to avoid them as much as possible, as he is no seaman himself. It's just a pity that deprived him of the possibility to explore another side of Nelson, and an important one.