OSX Mavericks introduced a few new battery-saving features: timer coalescing, App Nap and Safari Power Saver. On my early 2011 MacBook Pro, I’ve seen a legitimate 15-20% increase in overall battery life since upgrading to Mavericks.
However, I also noticed Time Machine was asking for a full backup almost once a week. This is frustrating because I push my backups over Wi-Fi, and a full backup (more than 100GiB) takes hours. That, and I don’t want to lose my backup history every week.