It was with great dismay that I read the changelog of v2.6. Version 2.6 apparently tracks the differences between versions of a blog post, like Wikipedia. I have a Wikimedia wiki on my website, and having to retain a record of every change causes the MySQL database associated with it to be much larger than the databases for my very active forum and frequently updated blog.
While a blog post won't normally see as many revisions as an article on a wiki, I will usually edit each blog post well over a dozen times to see how it looks so far, catch my spelling and grammar mistakes, alter wording to better convey my message, correct factual errors, add updates when new information becomes available, and generally improve the quality of my posts, even weeks after I publish them. While most changes are minor, I sometimes add or remove entire paragraphs. To me, writing is a process, and a blog post is never really finished. I fear that my approach to blogging will cause my MySQL database to become enormous, perhaps beyond the limits set by my webhost. I regard this as a feature that I don't want or need, and one that will be detrimental to me. I can't afford to upgrade.
I don't write this expecting a response, or hoping that my one vote against will accomplish anything. For what it's worth, I just wanted to be on record as saying that I regard this feature as a problem, and therefor v2.5.1 will be my last my last version of WordPress.