Update: As noted by Macworld’s Dan Frakes, this issue has been addressed in the recently released iTunes 11.2.1 update. If you haven’t yet updated, check the Mac App Store app or download the update directly.
One unexpected consequence of the recent OS X 10.9.3 update is that the Users folder at the root level of the startup volume is hidden from some users, though not all. I was among them. When installing the 10.9.3 update available from the App Store on both my 2009 Mac Pro and late 2012 MacBook Air, the Users folder was indeed missing. Yet I’ve heard from a couple of colleagues and several people on Twitter that their Users folders remain visible.
Thinking that this might be attributable to the kind of update I performed I downloaded the Mac OS X Mavericks 10.9.3 (Combo) update and installed it on my MacBook Air with the hope that it would fix the issue. Regrettably, it didn’t. The Users folder on that Mac remains missing. I even tried switching user accounts on the laptop with no luck. Regardless of which I tried, the Users folder was nowhere to be found.
Fortunately, there’s an impermanent solution to the problem. Launch Terminal (/Applications/Utilities), enter sudo chflags nohidden /Users
, and press the Return key. You’ll be prompted for your user password. Enter it, press Return again, and the Users folder will be visible as it once was.
What makes the solution impermanent is that it doesn’t hold across restarts. When you restart your Mac, the Users folder on affected Macs will once again vanish.
Until either Apple fixes the issue or someone figures out what exactly causes it (see note below), I can offer this fairly simple fix to the fix. Launch AppleScript Editor (/Applications/Utilities) and enter (or copy and paste) the following:
tell application "Terminal"do shell script "chflags nohidden /Users" password "yourpassword" with administrator privilegesend tell

This script will force an invisible Users folder to appear.
Or click here to open the script in AppleScript Editor
Fill in your real administrator’s password in place of yourpassword. Save the AppleScript as an application. Launch System Preferences, select Users & Groups, click the Login Items tab, click the plus (+) button that appears at the bottom of it, navigate to your saved AppleScript application, and click Add. When you restart your Mac, it will run the script when the Mac logs in, thus making the Users folder visible on affected Macs.
Update: Dave Hamilton at the Mac Observer seems to have sniffed out the root issue. As it turns out, this isn’t a problem caused by OS X 10.9.3, but rather some kind of interaction between iTunes 11.2 and Find My Mac. If you have the latest version of iTunes installed and, within the iCloud system preference, have Find My Mac enabled (even if you’re running 10.9.2), the Users folder will be hidden. Switch off Find My Mac, use the Terminal trick above to unhide the folder, and the Users folder will remain visible even after you restart.
However, if you reenable Find My Mac, the Users folder will disappear the instant you switch on the option. Therefore, if you want both a visible Users folder and an enabled Find My Mac, use the AppleScript trick listed here or take the suggestion of a couple of commenters and create an alias of the folder and place it in an easily accessible location.