The sim element of the game has always been good, even if somewhat unpolished. The "fire exchange" is the best yet, it's actually somewhat hard to hit and it isn't just point, click and kill with total precision anymore.
Long distance terrain textures are crap. Looks artificial.
Futuristic theme, as part of a now untrendy trend, is crap as well. Too much crysis influence, it's hard to relate. Modding is a hope though.
Underwater is a great addition to the game. Lacks in effects (bullets and water).
The current island is somewhat limited (i.e. the functional areas, just one town, few road segments, rest is wilderness which probably sees little activity), but they made a good job with copying the greek scenery.
However, my i7 920 can't keep up at realistic view distances (even though it should be somewhat limited due to fog from the sea). It still works great for all other purposes, so an upgrade won't be an option.