Leviathan clears up some history in the Mass Effect universe, but it feels rushed in almost every other aspect
*spoiler alert*
Admiral Hackett has received word from a scientist, Dr. Bryson, that he has discovered a creature that is powerful enough to take down a reaper. Curious, Shepard swings by Bryson's lab but before Bryson can inform Shepard of this powerful being, the Dr.'s assistant murders him (after he gains consciousness, he doesn't even remember ding it, like something was possessing him). Now begins your short termed career as a detective as you must locate this "Leviatan" as the creature is called and get it to help you stop the Reaper invasion. The story is interesting from the very beginning and it will change the way you look at Mass Effect's history by giving you some more information on the Reaper's origins. However, this plot doesn't affect your main game much and from what I hear, the ending hardly changes, which means you could just look up the story on youtube. Still, the storytelling is as good as ever and the emotional dialogue and voice acting is done well too, it just could have impacted the rest of the game a little more like other DLC add-ons in the series.
There are two types of missions in this add on; one good, one not so good. First, the shooting segments are as intense as always. I don't think they're as fantastic as LotSB, but the firefights feel very intense and exciting. You are only taking on Reaper forces in this mission so prepare to take on dozens of mighty brutes and shrieking banshees. One of these battles is especially immersive thanks to looking up to the sky to see harvesters and other reaper forces flying overhead. There are only 3 shooting sections and they don't take too long, but they're as fun as ever.
Unfortunately, this is broken up between mission with the sleuthing sections. Much of the time is spent in Bryson's lab at the Citadel searching for clues on the Leviathan's whereabouts. This is more like a point and click game which would be fine if there was more too it. It's so simplistic that all you do is wander the lab with EDI until you see something you can look at, something that will give you possibilities on where to search next. You can leave once you find enough or you can keep searching for clues to narrow your search. The latter is recommended unless you want to waste fuel until you find the right planet. Like I said, this part could have been interesting, but it just came out boring. It is about as simple as it gets and it takes up too much time. You'll be wishing you were in combat again.
*possible spoilers*
The biggest slap in the face though is the under water segment. When this DLC was announced, it was also said that it would include a section where you pilot a mech underwater in search for Leviathan. Sounds awesome, right? Well, it's not. There is literally nothing to this part of the mission, to the point where it might as well have been cinematic. Expected to fight reaper forces underwater? You're going to be disappointed, because it's nothing like that. You walk a few feet, you fall down a hole, you repeat that 3 more times, watch a cut scene, mission over......yeah, that's it. At least the visuals are cool, I just wish the rest of it was too.
The only other thing this add on offers are weapon mods from the multiplayer. Pretty cool addition, especially the omni blade attachment, but this alone is hardly worth the price.
It's been months since we've been asking for a brand new DLC add on for Mass Effect 3, hoping that Bioware can continue their trend of some of the best content money can buy. Unfortunately, this is not one of those add ons. Sure, the action is intense and the story is interesting and changes the way we look at Mass Effect lore, but it feels rushed at the last second, like it was supposed to offer more. It takes 3 hours to complete but even Lair of the Shadow Broker used its time wiser than that. Too much time is spent on the boring detective work and the under water portion was over hyped. It's not a bad DLC overall, but I only recommend it if you are a die hard Mass Effect fan and want as much story in your Shepard's story as possible. Otherwise, save your money.