Cavalary: Nope, just tested, still 10k characters.
Okay, I must have had a uneven amount of quote tags, then. :/
Thanks for the correction. :)
OT:
I completed XCOM
Enemy Unknown and the expansion
Enemy Within, and now I'm playing the
Long War mod.
Pro
Enemy Within adds a fifth-column element, with a group equal and opposite the player's trying to use the alien technology for their own gain, rather than helping to defeat the invaders (which may or may not be a goal, too).
For gameplay, it adds a number of improvements, like a new resource to collect (Meld, which is used for genetic augmentation and also for soldier cybernetic enhancements) voiced banter in a half-dozen languages (colloquial phrases in German, French, Spanish, Polish, Russian as well as English, which make a huge difference to me).
Contra
It does reverse the camera orientation buttons (the camera can be spun clockwise and counterclockwise, but the buttons were right and left and now they are left and right, with the same arrows, so now I am forever hitting the button three times to spin the screen orientation to where it would have been if I had pressed the other button once), since the game allows for four perspectives of the tactical map.
The Long War extends the game (since research of the technology tree will be complete well before the final battle) and adds a number of changes to the combat statistics. As I noted, I'm only part way through the mod, so I can't comment on it properly yet. The combat is certainly much more difficult, but the difficulty is well managed and not too steep.