I found Caulaincourt valuable for his narratives about what he and N. discussed prior to war 1812. Hearing what N. actually said was very telling to me. To me, one of the most interesting issues is exactly what N. said prior to the start of war. It seems to me that understanding how this one decision was made is to understand N. Caulaincourt seems to be a well respected source for this.
I also thought Caulaincourt was invaluable for information about the situation with the horses. -Of course, the horses are often described as being a critical issue.- Many of the horse issues described by Caulaincourt don't appear in any other work on 1812 - although I'm sure there has to be a book dedicated to the subject. Caulaincourt describes how early on the horses were unshod because the needed equipment wasn't available, that horse neglect was often intentional in order to be released from the burden of caring for them, that the cart wheels were not the type needed for moving in the sandy soils they encountered. These sort of details of Caulaincourt's reporting ring true and I can see no reason for him to slant things.
Who else do you want to hear from other than Caulaincourt for a discussion about N. overstaying in Moscow? Who else can you listen to about what N. said on his long journey back to Paris?
One thing I picked up on was how for N. that Austerlitz became a real problem. Statements by N. to the effect how dare they -whatever- to the winner of Austerlitz. It's wasn't so much what was said, which was always arrogant sounding, but how often it was used. Austerlitz seems to have been constantly on N.'s mind.
Anyone's views on Caulaincourt are meaningless; Caulaincourt's views on anybody are meaningless; but, his real-time reportage is fascinating, invaluable, and often irreplaceable.
I'm well aware of the problems with memoirs; nothing can be taken at face value. But, with care, and all BS detectors at full gain, memoirs can be an essential tool of history.