So, I finally finished the game last night (soldier difficulty).
You can tell that the game is really unfinished and just had pieces patched in by different people working on it.
The pathetic ending is not just a cliffhanger. When it ends, there is no flow. No end credits, just mission over and return to the main menu. As if they literally added the final cutscene and said go, go, go, get it gold to be over with!
I also played the first 3 chapters co-op (Ubadass) with 3 other people and I didn't get the improvement some people are claiming to be.
It wasn't harder, just cheaper when fighting Mercs and with less health.
The MP while not bad is nothing special and needs serious balancing.
The biggest let down with this game is that it really had potential. In the hands of a developer that actually gave a f@ck about polish and production value this could have been a great game. Shame!
And yes, the demo they showed and the amazing screenshots before release was a different game. This was false advertising.