My home Mid 2012 MacBook Pro with HDD and 16GB ram works faster than it worked with Mavericks. Surprised me. For example, switch between users is much faster than before. But then I looked in the system monitor, and around 10GB ram is being used, and that's with browser, finder and a few lightweight apps. Noticed a few instabilities,- f.e. virtual machines crashed several times which never happened before. Will not upgrade my business Pro until they issue an update or two. Activity Monitor shows a bunch of "Not Responding" processes. That might be the reason for battery drainng fast.