GMail has been improved in ways other than UI changes. They have rewritten the HTML, CSS and JS to make it more hackable for Greasemonkey - and in the process,

GMail has been improved in ways other than UI changes. They have rewritten the HTML, CSS and JS to make it more hackable for Greasemonkey - and in the process, optimized that HTML, CSS, and JS to reduce number of connections and subsequently load time. The backend has seen massive scaling. They added POP and IMAP. I don't know what I would change for GMail. It's a strong email client that gets the job done. I wouldn't consider it "worrying".