Mr. Bennet changes in several ways though they may not be completely good changes. At the beginning of the novel Mr. Bennet is rather passive and uninvolved in the lives of his daughters, particularly his younger daughters who he considers silly and frivolous. His lack of a firm hand is partly to blame, according to Lizzy, for Lydia's scandalous elopement with Wickham. After Lydia's embarassing escapade he makes an extreme reversal and vows that Kitty will never be able to even go to a ball. This reaction is just as inappropriate as his previous choice of non-involvement and the reader is left hoping that his extreme reactions will ease later on. Also, Mr. Bennet changes in his opinion regarding Mr. Darcy. Based on the reactions of his daughters to Mr. Darcy, he was not inclined to like the man at all. However, as he trusts Lizzy's judgment implicitly, when she changes her mind about Darcy, he does as well and allows the marriage.
Static characters (those who don't change) are most prominently, Mrs. Bennet, Lydia Bennet, Catherine DeBurgh, Mr. Collins and even, arguably, Jane and Bingley. Jane is completely affable and forgiving from beginning to end of the novel. Bingley is easily swayed by the opinions of others from the beginning to the end of the novel. The reason that readers forgive these characters their static behavior is that we enjoy the end result of their character trait in action. In other words, because their flaws are minor and they are likeable characters who end the novel happily, we forgive what may be perceived as minor character flaws.