A french review of the game :
http://www.gamekult.com/tout/jeux/fiches/J000076370_test.html
it rates Defcon "good" (7/10) for single player games. And "Excellent" (9/10) for multiplayer.
Gratz Introversion for these reviews.
a quick translation (sorry my english is not very good) :
"Yes, it's still possible to make an addictive and fun game without next gen graphisms. Even if
the perspective to annhilate entire cities under atoms rain is nothing to laugh about, Defcon
still manage to make the immoral completly fun. With its gameplay that first seems simplistic,
but reveals treasure of strategy, its unique graphic style and an atmosphere to please the doctor strangelove that sleeping in us, the new game from the creator of Darwinia is a ludic UFO. Defcon is not a gadget : it's a real game, a fresh variation for the real time strategy genre. Deep but accessible, with great multiplayer, Defcon is an excellent surprise, maybe not the game to stick with all winter, but the ideal game for time to time play. There are really worth ways to spend 15 euros."
edit : for the translation