The most significant changes from the PTR haven't been included (yet). Neither will Druids be able to cast roots indoor nor will some Shaman totems work for the whole raid. The most major changes are probably mounts being available from level 30 on for 35 Gold and the re-balancing of the Rogue skill Cheat Death which has been weakened.

As usual, the latest patchnotes can be found here.

Please make sure your add-ons are up to date if you experience malfunctions or errors.