All memoirs are personal and therefore limited in value. Past historians have often over-relied on them but some also over-relied on the Imperial bulletins and other official propaganda.
Not everyone who knew Napoleon liked him, that is hardly surprising nor is it surprising that some of them changed their opinion of him over time. If they kept their thoughts to themselves while he was their employer and only expressed their opinions after leaving his employment, that is not surprising either. Most people would do the same, particularly if one's employer had the power of arbitrary imprisonment. he was flattered outrageously while he was in power which is less excusable.

Susan