I realize that I'm rather late to the party here, but I just finished Minerva's Den and had to talk about it.

If this storyline had been stretched out to full-length and been called "Bioshock 2" I would have been overjoyed with it.  The weak storyline from the main game (and the flimsy twist at the end) left me wanting so much more from a return to Rapture, not even coming close to the glory of the first game.

As it stands, Minerva's Den must be 2K Marin's "apology" of sorts.  The DLC fixes all the problems of the base game in the span of about four hours, and what a four hours it is.  The first thing that is immediately noticeable is the sense of power felt in the shoes of Subject Sigma.  I took down rooms full of Splicers with ease, almost right from the get-go, and rarely felt the shame of using a Vita-Chamber.  The action is almost non-stop and the gunplay is an interesting as ever, especially with the addition of the new Ion Laser.  Weapon upgrades are now found on fallen Big Daddies, rather than through the traditional "Power To The People" machines, which I felt was a great way to streamline the process for such a short game, but the new Plasmid, "Gravity Well," left me underwhelmed, personally.

The visuals are impressive as always, and the design of Minerva's Den's three levels left me totally satisfied.  Pipes and computer screens line the walls, there are cameras around almost every corner, and the Splicers are as vicious as ever.  The new Lancer Big Daddy is also quite imposing and possess its own unique visual style.

The plot is a much-needed improvement over Bioshock 2's.  The tale of two partners turned enemies, with Subject Sigma caught in between, escalates to a fever pitch with incredible pacing, finally climaxing in a mind-blowing finale that nearly rivals the "NO WAY" moment of the first game.  Make sure you hold your head to stop it from spinning.

In all, for Bioshock fans that were disappointed by the weaknesses of Bioshock 2, look no further than Minerva's Den.  Download it now.