You should hit the blog post below for information on the full patch but the short of it is that there will be a new interface for crafting materials so they no longer take up inventory slots. That alone is worth the price of admission but 2.5.0 also contains The Armory which gives each of your characters 5 unique armor loadouts you can toggle between. On top of that they are adjusting the rate at which certain Adventure mode zones spawn making the ones that show up a bit too often less seen. There are a couple other things in 2.5.0 so hit the link below for more details.
And if Blizzard is reading this... please... Another couple acts of Diablo III please?