The Darcy in my head far out paced the Darcy of this book. I found Slater's Darcy rather dull, with the many of his entries consisting of detailed descriptions of what he ate that day. There was an attempt to add some spice with mentions of Darcy's trysts with chambermaids and his attempt to help Bingley get over Jane by setting him up with a kept woman. While not unfathomable, I didn't like the idea of some of my most beloved characters acting in such a manner. It is hardly consistent with the idealized version (complete with pedestal) that I have in my head.
After Darcy's first failed proposal, the novel did pick up a little steam for me, but not enough to make this a worthwhile read. While not the worst I've ever read, I cannot say that you will be missing anything if you don't pick this one up.