This does come with a slight downside, as the developers had been planning on giving everyone an extra character slot to include the Dark Knight, but there are currently some technical issues cropping up due for a hotfix tomorrow.
https://twitter.com/BDO_News/status/834396122072379392
Still, it’s a new class for those who like it, and it’s just a week away at this point. You can check out screenshots and an overview trailer just below, or you can just create a face you’ll like as soon as server maintenance is finished.
https://www.youtube.com/watch?v=78gi1U4Fb7w
Source: Dark Knight announcement, Patch notes