WARNING: A new "HD version" of this game has been announced. It will be an entirely separate game and include all DLC content. Most importantly, this "old" version (released May, 2014) WILL NOT update to the new version, which will be sold separately.
The new version of the game will contain new enemies, events, multiplayer enhancements, and graphical updates not available in this version of the game. Furthermore, the two versions of the game will not be compatible with each-other for online play, nor will saves be compatible between games.
It is worth noting a patch for the "old" version will include some of the new content, such as a new NPC and SOME of the new enemies and events. However, the remaining content will be exclusive to the new version.
Therefore, it is my recommendation you avoid purchasing this game, as the new version will arrive April, 2015. I also strongly encourage you to scrutinize the business practices exercized by the developer and publisher of this game. To make a very long story short, it is my opinion we are being sold the same game again with minor, though desirable improvements. In most circumstances, this would be called a support patch.
SOURCES: The community has requested I add links to the sources of compiled information. While this sort of business practice may seem unbelievable, it is true.
Steam thread confirming differences in "old" and "new" versions:http://steamcommunity.com/app/236430/discussions/0/624076027426323183/
Famitsu Interview: http://www.reddit.com/r/DarkSouls2/comments/2nqqjm/famitsu_interview_tanimura_refers_to_ability_to/
I take no credit for producing any of the content in the provided links/video.