The first add-on for XCOM: Enemy Unknown will be released next Tuesday, November 4 for $7 (UK price to be verified). The Slingshot DLC includes three council missions (you must start a new game to play them), as well as a selection of new hats, helmets, and armor decos. I played all three new missions earlier this week, and my preliminary verdict is: well, they're alright. Are they what we wanted, though?
The missions are interspersed throughout the game, and tell the story of an alien battleship headed for China. I'd never have worried about spoilers in XCOM before, because it's tough to spoil a story that's largely told in the mind of the player. In this case, I guess you should stop reading if you don't want to know how the China invasion plays out. It's not a shocker, really.
The first mission is an escort mission: save Triad defect Zhang (why did he defect? who knows!) and he'll give you a briefcase containing some alien something-or-other. Except for actually looking like some version of China, it isn't different from any other escort mission. After the mission, however, Zhang joins your barracks, giving you access to a high-rank soldier earlier than usual. The catch: he's not customizable and will always be Zhang. For me, that means he's benched.
The second mission has a 10 turn limit: the goal is to activate thingamajigs on a subway train intended to divert the approaching alien battleship. The turn limit makes it the most difficult of the three missions, and I failed because I didn't realize that after activating the thingamagics (transponders? they're probably called transponders) you still need at least one turn remaining to get someone to the train's control cabin. Oops. But aside from that, there are no surprises—as usual, Thin Men drop, somehow, from the sky of the underground train station every time you push up far enough to trigger reinforcements.
The third mission is the best, because it lets us do something we've been wanting to : invade an alien ship in-flight. As your soldiers trek across the battleship, they're tasked with shutting down power cores to disable its ability to ominously hover over populated areas. And when that last power source is dark...you've finished the DLC. At that point, you have Zhang and access to certain technologies earlier than usual.
The missions are fun because XCOM is fun, and they're designed the way other good XCOM missions are designed. That they look like they take place in China is nice, if only in comparison to Everytown, USA and This Is A Forest, USA. That they give you access to a non-customizable character is...well, I don't play XCOM for XCOM's characters. And getting access to existing technologies earlier isn't really exciting after having already played the game.
I haven't yet played the missions in the context of a full game (Firaxis had saved games prepared at the start of each), and that experience will inform the final verdict. They should fit in well, but I wonder if, two or three playthroughs later, Zhang's clockwork reappearance will only make XCOM feel more predictable.
If you weren't planning on another playthrough, Slingshot probably won't bring you back. It doesn't add anything radical or contribute to the unpredictability that makes XCOM so enjoyable for so long. There are no new weapons, no new research or facilities, no new aliens, no new mission types, no base invasions, no grand mission to the moon.
Slingshot interprets "add-on" in about as plain a way as possible: three missions and some aesthetic items. Actually, the new helmets are the best part. The baseball caps and intimidating masks still don't let me design soldiers just how I want, and I still wish character customization were much improved, but it's a start.