WARNING: SPOILERS FOLLOW AFTER THIS POINT
But not super into detail. Read at your own risk.
So, what does Lair of the Shadow Broker do right?
Freshens Up Gameplay
Everything you like about playing Mass Effect 2, but they bring some new tricks out, especially in the boss battles. Have you fought a charging Vanguard yet? Now you will. Have you ever had to punch through someone's shields? Now you will. And you will feel like, as Zaeed would say, a guddamn hero
after you do it all.
Continues A Story in the Universe
Liara's has been chasing the Shadow Broker for quite some time. You can finally interact with a character you haven't had a chance to connect to from ME1, and you can help her with her quest. Your romance with Liara can continue too, if you want it to or if you had it in the first place. And this is something that is obviously a set up for ME3. Also, this dlc is for the endgame, so you don't have to feel stupid doing this after the big endgame mission.
Rewards You For Playing
You've probably already finished the game, so you might need more incentive than just "Another even BADDER dude" to get the dlc. Well there are a ton of extras. You get info about your team, hilarious videos, and a bunch of perks to use for your entire squad. It is what makes this DLC worth every freakin' penny.
SPOILERS ARE OVER
All in all, this is a dlc worth playing because of the fact that it rewards the hardcore fans with everything they appreciate about the game and then some. If you're on the fence about buying it, do it! You'll appreciate it. I give it a 9.5/10 because of course it can't be perfect, but it's pretty close. At least, for a diehard fan it's pretty close.