Pretty damn good for a DLC
The story is pretty solid and the ending is satisfying and with a twist. The voice acting and art direction is still as is impeccable as it was back in 2007.
There are some new weapons and a couple of new plasmids, but they are not that useful so you will probably stick to using the good old regular plasmids. There's enough exploration to warrant going through every filing cabinet and every cornet of the map.
There are some frustrating slightly over-whelming moments but nothing you can't handle.
I haven't played Bioshock 2 in two years but I have absolutely forgot how awkward of a port it is. The aim-assist is in your face, the mouse controls are the same as if you were using a controller to aim, the textures sometimes take a second or two to load, and my highest resolution (1920) barely yielded any results - everything is in your face so you have to sit further back from the screen to be able to capture everything. It felt like I was playing on a 800x600 resolution, seriously. But at least there is Directx10 lighting which you only see on rare occasions.
Aside from that, you get to visit Rapture as a new character, as a new Big Daddy who is trying to get to the Super Computer or the "Thinker". This machine has calculated everything there is to calculate so by using the law of determinism your fate is already set, except that you don't know it. So you basically play out your script and eventually find out what the whole fuss was about it.
I am also a bit disappointed that they didn't take the concept of robot little sisters further. I thought there was going to be a whole new subplot, but there wasn't. There are a few audio tapes that accompany the subtleties of the Rapture society including a few homages paid by Andrew Ryan himself.
All in all, this is a pretty good DLC that only costs $ 5.00 on Windows Live Marketplace.