Great DLC. Might be a novel tie in.
All that said though, it's still Mass Effect 2 and there aren't any gameplay changes or any new weapon or any such thing. But you must get this dlc for the story. Bioware recently announced that they'll be releasing dlc content that will patch the story till ME3 comes out, and if I'm not wrong, this might well be the first of them. It's story most certainly has a striking resemblance to the synopsis of the upcoming novel, Mass Effect Retribution. This might well be a step in the story, leading to the events of Retribution. (That is what I can make out anyway).
The dlc does have its 'Oh Snap!' ( :P ) moments. And the ending sequence specifically is quite memorable.
So all in all, I'll recommend this. Have fun playing.