Simply the best part of Mass Effect 2.
For starters, Lair of the Shadow Broker is perfect in just about every way. The combat hasn't changed, so if Mass Effect 2 wasn't your fancy for mechanics don't look here. However, this DLC features the two best boss fights in the game, two of the most impressive levels. The visuals are top notch. The locales are unforgettable, and when you think back to remember the best of Mass Effect 2, you will undoubtedly remember the majority of this DLC. You'll get the chance to catch up with Liara too, and a few new achievements to unlock as well. The plot is also top notch, so expect some good story and a few things you didn't see coming.
The only problem, at all, with this game is that it is short. It should only take you between 2 to 3 hours to complete. However, these hours are non-stop full-octane entertainment, and not a second feels wasted or tedious. I kind of wish Liara would join your team afterward too, but that's not the case.
After the mission, be sure to explore the entirety of the "Lair," there are some great consoles to interact with if you're a big Mass Effect fan.
The bottom line: If you have Mass Effect 2 and 10 bucks you must get this DLC.