For the ultimate good
Not unlike what Rockstar is offering with the current-gen ports of Grand Theft Auto V, Blizzard has confirmed that players will be able to bring over their characters and saves from the Xbox 360 and PlayStation 3 versions of Diablo III into the Xbox One and PS4's Diablo III: Ultimate Evil Edition. Yes, this even includes transferring saves from the Xbox 360 version over to PS4 and from PS3 to Xbox One. There is no option, however, to transfer saves between Xbox One and PS4.
Transferring is a fairly simple affair -- once your Gamertag or PSN ID is linked to a Battle.net account, the rest of the process is handled through in-game menus. No fidgeting though widgets, install tools, or other systems when at your PC.
Diablo III: Ultimate Evil Edition will release on August 19 for Xbox 360, Xbox One, PS3, and PS4.