First off Blizzard has pointed out that this patch unlike many other will not be aimed at class balance but changes to the class skills will be more to take into account of the other new features such as the new legendary sets.
Speaking of the Legendary sets, Blizzard announced 3 brand new sets that rival the most powerful sets currently present in Diablo 3, these sets are – Unhallowed Essence, Wrath of the Wastes, and Delsere’s Magnum Opus. The changes to sets don’t stop there however as some of the other sets in the game will receive tweaks and re-designs as well as adding bonus’ to a few. 15 new legendary item powers have also been added in the of of rings, armor and gems.
Love to chase those goblins? of course you do and now there are 3 more to chase down. The Gelatinous Sire splits into smaller goblins, the Gilded Baron helps satisfy your never-ending greed for gold, and the Insufferable Miscreant has friends to help him run interference. Find them and collect your loot.
For PC and MAC players there is a technical update which changes the game files compression and storage type. Blizzard is changing this to there own proprietary file system which gives many benefits including the ability to hotfix games an improve the patching system. *This update will not apply to console players.
There are other smaller updates and more details on the ones above at Battle.net