I'd say the only WotC downside is that it's you know, a tiny little ONEME.
I have no idea of what's supposed to mean, but generally speaking I would say that the only real downside of WOTC is how it's more than a bit on the "cheesy" side when it comes to narrative and overall tone/mood.
The over-the-top "chatty villains who send you hatemails" have a saturday morning cartoon vibe more than anything.
But given that frankly speaking the franchise was always garish as fuck and only petulant wankers cry about "muh narrative depth" in a tactical game, I feel completely justified in saying that one has to be a top tier retard to buy the full package and then avoid the DLC/expansion that on a mechanical level makes the entire game orders of magnitude better.
WOTC includes:
- A lot more visual assets, types of maps and types of missions
- Some significant improvements in your base-building, with few very impactful changes and additions.
- The zombies/lost, that add a very enjoyable variable to the way you can (and should) approach combat when they show up.
- Two new EXCELLENT classes, not just powerful (and boy, they are) but a good vehicle for entirely new playstiles... and a vaguely serviceable one (sorry Skirmisher, all things considered you suck).
- Some of the best equipment in the game.
- Interesting elements of randomization to the soldiers (they all come with an unique and randomly generated skill tree and some variations in the base stats, now. That makes each one to some degree unique).
- last but not least, the game changer that is the Fatigue mechanic, something that actively forces the player to rotate different teams rather than encouraging you to stick just with your best one. This also pairs tremendously well with the new "Covert missions" and other multiple ways to level up all the other generally-inactive soldiers.