Fantastic story, great visuals and awesome unlockable features makes this arguably the best Mass Effect 2 DLC to date.
You are given intel on the Shadow Broker, and start out by handing off the information to Liara T'Soni, one of your former crewmates, now on Illium working as an information trader. After a while, Liara joins your squad, and you can direct her as any other teammate, distributing her skill points for different abilities. You'll be fighting through hoards of soldiers from the Shadow Broker's personal army, who are comparable to the Eclipse mercs from the main game.There are no new weapons in this DLC, but the adversaries are armed with a new item: flashbang grenades.
The Shadow Broker sent an assassin to take Liara out, and it's your job, alongside Liara, to defeat the assassin. Once you've dealt with them, you'll take Liara and one of your squadmates to infiltrate the Shadow Broker's stronghold.
I'll not reveal who the Shadow Broker is, but Mass Effect fans will not be disappointed. After you confront the Shadow Broker, there are some nice features that are unlocked for future use. There are mining "investments" that Shepard can put money into, and shipments will come in with minerals periodically. There are also more detailed dossiers on your squad, outlining details about their personal life and activities they partake in outside of going on missions, some quite humorous.
Overall, this DLC package is well worth the 800 Microsoft Points, in my opinion, and adds 5 new achievements for 200 gamerscore as well. It has a fun new mission, a great story that puts more pieces of the puzzle into place, hinting more and more at what's to come in Mass Effect 3, and nice features that look promising.