X-COM enemy within
for those of us who have been with the X-COM franchise since it was first released 
I managed to finagle through a sale, an additional discount and a coupon the price down to something actually reasonable for DLC, and have played through the DLC part twice now.
PROS:
Cybernetics for soldiers
Genetic alteration for soldiers
New Council Missions
New Weapons*
2 new mobs
CONS:
Cybernetics and Genetic labs show up too late in the game to be really worthwhile, no matter how hard you push them.
*New weapons are almost to the one, only re-skins of tier 0 and 1 (guns and lasers)
It definitely adds something to the game, however it is hardly worth even the sale asking price at $22. I would suggest waiting until the price falls under $10 to see any value in it, no matter how much you wish to cut the arms and legs off a soldier, slap them in a mech and watch them kick Exalt and alien tushies.
Also the final mission for Exalt (introduced in this DLC) is a joke....takes about 4 minutes, and rewards nothing in tech or cash, just the usual mass aoe of a few gene soldiers <you will be used to it by then>.