This DLC, like Mass Effect: Genesis before it, is designed to help players keep caught up on the story and make some key decisions from ME2. The downside is that this is less helpful than playing ME2. Some decisions kill off a lot of characters easily and make unavailable for ME3. I'd recommend playing ME2, as it is still a phenomenal game. If you only have ME3 and this comic, well, just make sure to get a guide to using this effectively.