A decent addition to the core game, but loopholes keep it from being a truly great extra chapter.
The gameplay isn't any different from the core game, so if you enjoyed that, you still have plenty of options here. For a small package, a DLC I managed to beat in about 5 hours, there's a lot packed in. There are a few side-quests, an important choice to make that should have you coming back a second time, and thank god the final "boss" fight doesn't force your hand like the core game. Seems Eidos learned from that. Yet, the back and forth you're forced to take seems almost like a chore in the vein of fetch quests. You're forced to backtrack quite a bit, making the environmental design feel slightly limited. In a Deus Ex game, a feeling of limitation goes a long way where it might not otherwise.
The biggest issue here is the story. There are elements here that don't seem to make sense. Jensen acquires a lot of info here, and the fact that he knows certain things would ultimately change the core game from this point on. It leaves a bit of puzzling. This may be balanced out by fanservice in the form of certain character and elements that pertain to the original game, even hints that you are in fact in the very same environment that JC Denton will find himself in many years later. However, the story still ultimately feels like it doesn't add much to Human Revolution. Certainly, it's just a DLC, just another extra chapter or story. In this sense, it's a fun little addition to Human Revolution.
If you enjoyed Human Revolution, Missing Link is worth the buy. Although it feels like it should be slightly longer, even for a DLC, it has what any good DLC should have: more of the same. Anyone considering themselves a Deus Ex fan should pick this up, if at least for the....savage.....Deus Ex goodies.