The new DLC for Fallout:NV is truly great! If you enjoyed Mothership Zeta on Fallout 3 this new DLC will be right up your street. Proper LOL moments when interacting with the main characters. Some of the nods to the 50's american sci-fi movies are immense.
I haven't played through it all yet but the way it's heading this COULD be the best DLC so far - up there with Shivering Isles on Oblivion.