Far Cry Instincts Evolution is more of an add-on than a full fledged sequel, but still very fun to play.
The single player is expanded by new storyline elements, new weapons, and slighty altered feral abilities. But the truth is that this ''sequel'' dosen't expand on the original the way it could have. Far Cry Instincts seemed longer and far less glitchy than Evolution, the new feral climbing elements can get you rip-your-hair-out pissed off, and the overall campaign is shorter than FCI's was.
However, despite the subpar campaign mode, the map editor and multiplayer really have saved this game from getting a lower grade.
The map editor has been honed, new brushes for your maps, new terrian sets, new options such as the square cursor for doing corners or the new undo feature that can replace a deleted object, etc...
The multiplayer is also decent, though not really improved over FCI.
It has more glitches, but also allows for quicker, more fun gameplay,
turrets, ziplines, new weapons, new vehicles, etc.
So overall, I would say that you should rent this game first before buying, especially if you have never played a Far Cry game. But if you are a hardcore Far Cry fan, then you will find great enjoyment out of Far Cry Instincts Evolution. I give it 7.8 out of 10, almost as good as FCI, but not quite...