The final game includes 20 (Preview version includes 5 maps).
As many have "feared", there will be monsters (Gen-manipulated). The preview version contains three different monster-typs.
On the whole the KI shall be okay except for a couple of quirks which speaks into it that some opponent at fire running "stupid" in the area around. However, this is still up to by fixed till the final version.
By the high level of difficulty it is better to plan your attack. A frontal attack will cause heavy damage.
To the graphic much doesn't have to be said. Reflective water, living gauze & fauna (birds, fish, insects, ...), insanity visibility ... . FarCry will become a milestone for certain in the Shooter history, as once D**M.
A detailed article (only in german) you'll at GIGA.de.
Note: The mentioned Preview version isn't available for the public!