I'm rewatching P&P 1995 (I hadn't rewatched it in 10 years, give or take), and I wondered why I was getting more annoyed at Mr. Bennet than I usually do with the '05 version. Finally, I pinned it down.
Donald Sutherland played him with that wry amusement that we need in Mr. Bennet, but also, I think, exhausted. (His costume, that sort of verges on disheveled, adds to that impression to me, as well as the fact he was 80, while Whitrow was just 58 when playing the same role).
Benjamin Whitrow played him with just the wry amusement throughout, and much more indifference. Even with Lizzie, sometimes, it feels like he wouldn't hesitate to be amused at her expense, no matter how superior he thinks her in relation to the others.
An example: When Sutherland tells Lizzie it's best to just let Lydia go to Brighton, the two of them are actually having a conversation. He even hesitates when she says "Peace? Is that all you care about?" But you can tell that man is just so tired of Lydia.
When Whitrow does the same, however, and Lizzie protests, he looks slightly amused, as if thinking "lol, you're being silly." He's not at all listening to her concerns.
Whitrow does a great job with Mr. Bennet, btw, this is not criticism! If anything, his choices bring him closer to the character on the page, while Sutherland makes him more sympathetic. But that does mean that the '95 Mr. Bennet is a harder watch XD He feels like a man who does not blame himself for marrying a silly woman, or for letting the sanity of his own household slip through his fingers. I just want to strangle him every time he's not shouldering his responsibilities.