Apart from being able to use the new "rune system" on each and every spell that you have, you also get six active skill slots and three passive skill slots, all to be unlocked as you level (as opposed to being able to mod your UI, so that you can have all of them laid out). You start off with only two active skill slots, and you unlock more as you level up (you gain an active skill slot every six levels past 6, and one passive skill slot every ten levels past 10). They've also announced two new items, to aid you while you quest. The Cauldron of Jordan is an item that allows you to sell your unwanted items as if you were in town (much like your pet in Torchlight, but without the travel time), and the second is a "revamped Horadric Cube" called the Nephaleim Cube. Apart from those nifty tools, your stash is now shared between all of your characters!
My biggest concern though is the fact that you can use REAL MONEY to buy items in-game! Blizz has set up two auction house systems (both are stocked by actual players, not blizz), one similar to the AH found in WoW, and the other using real currency. The money attained through the AH can be used to buy stuff off the Blizz store and fuel your WoW account. They've also said that the money can be redeemed through a third-party payment provider, at a cost. This opens the game up for some serious abuse. If they thought that they had problems with gold farmers, they'll be in for a world of hurt, when some dicks with access to cheap labor decides to abuse the system for real gain. *COUGH*Chinese gold farmers*COUGH*
All in all, the new changes are pretty good, and they allow for tons of character customization and experimentation. I’m just really worried that D3 might turn into WoW with real life money at stake, open to scheming opportunists. I guess we can all just hope for the best at this point. After all, we already knew that Blizz would eventually go “full-on dark side” when Activision bought them like cheap whores.