The Dark below i would say no, there's one raid that's really a lot less in depth than vault of glass and a strike that's a bitch and the story is kind of weird. If you're going to get one, get house of wolves. The prison of elders game mode is good, the story telling is much better and the story is actually fun. And if you're into PvP, the new PvP event is a nice competitive mode.

Source: around 600hours in destiny