The DLC was originally meant to be released on the 25th of March for Premium members, although the delay of the Xbox One version meant that non-Premium members had their release delayed too otherwise it wouldn’t be fair to Premium members who were supposed to get their hands on it before everyone else.
According to EA, the reason behind the delay was because they felt that it just wasn’t up to scratch yet, and given the amount of backlash and even lawsuits that EA has faced over the buggy release of Battlefield 4, it seems that EA has learnt their lesson and will not be rushing out the DLC, so presumably the game is now good to go.
If you’re a non-Premium member, you can look forward to the DLC released on the 15th of April where you will be able to get your hands on it for $14.99. More information regarding the DLC and its release can be found on its official website.