Good: Funny as hell, and really enjoyable, must-buy for anyone who has not finished ME3 yet.
Bad: Some turns of the story predictable, short ~3,5 hour.
It is short. The story is interesting, but doesn't demand from you much thinking. After being on 52 lvl you pretty much cant do anything with skill point that you receive with next one.
But.. what happens after the "main story" of the DLC ends is just a pure fun. The humor in dialogues is the main and most "visible" attribute of Cytadel DLC. But here is one question that should be asked - "Why wasn't it in the original game?!". It would've been so much better when I played ME3 first time. Playing it after seeing the ending of ME3 gives you the feeling "Why so late? Why not then when ME3 was released?".
All in all I recommend it for every ME fan!