I am certainly aware of the habit of overblown dedications in books of this period, although I thought the language for a sergeant to be especially flowery. Perhaps he had an editor or ghost-writer, as a number of folks did back in the day.
I read the first couple of chapters and skimmed the rest. As I said, it's a fascinating little book. With regard to its value vis-a-vis memoirs, I thnk it is as easy--and just as likely--to expand and augment "contemporary notes" when it's time to publish them, even if it is a few months after they were originally made, as it is for memors published years later. The same claim has been made regarding the accuracy of Napoleon's correspondence and many of the bulletins--they were written immediate to the specific time and incidents, but with a certain twist for effect, shall we say?
As far as I am concerned, if you have to put the word "impartial" in your title, then there is a problem somewhere. Impartiality is a judgment call, and one best left to the reader to determine.
"The other side," in my frame of reference, have always been the Allies.