Apple have made OS X 10.9.3 available for download via the App Store or direct from Apple site here;
OS X Mavericks 10.9.3 Update (Combo)
I put the link to the Combo version as I tend to prefer that way but their is an incremental version also available.
Noted updates include:
The OS X Mavericks 10.9.3 Update is recommended for all Mavericks users. It improves the stability, compatibility, and security of your Mac.
This update:
Improves 4K display support on Mac Pro (Late 2013) and MacBook Pro with 15-inch Retina Display (Late 2013)
Adds the ability to sync contacts and calendars between a Mac and iOS device using a USB connection
Improves the reliability of VPN connections using IPsec
Resolves an issue that prevented Font Book from installing PostScript Type 1 fonts
Improves reliability of copying, editing and inspecting permissions of files on an SMB file server
Improves reliability of network home directories
Improves stability when installing configuration profiles
Improves login speed for users in Active Directory groups
Includes Safari 7.0.3
source
They were testing graphics drivers during beta phase so hopefully they have updated those some also.