Great stuff. There's just not enough of it.
Other than its brevity, there is little to complain about here. The Shadow Broker has been a great part of the background lore for both ME games, and it's great to finally learn more about him. It's also great to catch up with Liara, who was disappointing to say the least in ME2. Now if only they could come up with something similarly cool for Ashley... but I digress.
The combat is still the same intense affair it was in the sequel. The level design is rather better, though. It seems due to the shortness of the pack the devs really managed to figure out the layout without employing the ridiculously placed cover you may remember from ME2. Also, when they decided to create "atmosphere" for the game, the good folks at Bioware seemed to take the task literally. I'm sure you've heard by now about the Shadow Broker ship sequence, but it must be seen to be appreciated.
Throw in a vehicle sequence and two boss fights, and the Shadow Broker begins to sound like a full-scale expansion... It would be, if it wasn't two hours long. Great stuff all around, just not enough meat.