Activision is offering an enticing offer for Destiny that will be of particular interest to anyone who hasn't yet invested in an Xbox One or PlayStation 4. For a limited time, buying a digital copy of Destiny on Xbox 360 or PS3 will entitle you to a free digital copy on Xbox One or PS4.
The deal has very few catches--you simply need to buy the game (or season pass) by no later than January 15, 2015. Because it's a digital copy you have to buy, there won't be any way to then give your old game to a friend, which is likely why Activision is willing to offer this.
The last-gen version you buy dictates which current-gen version you can upgrade to. In other words, if you buy the PS3 version, you'll only be able to get the PS4 version, while the same holds true for Xbox 360 and Xbox One. Either way, upgrading to a current-gen version won't prevent you from continuing to play your last-gen copy. And because your progress transfers between platforms (within the same console family), you won't leave to start over when you move from PS3 to PS4 or Xbox 360 to Xbox One.
For those of you who considered getting it on both PS3 and PS4. Save ya some money.