Hmmm. FC3 was absolutely fantastic. But it's only been 2 years so I hope they haven't pulled a CoD on us and just reskinned FC3. I mean one of Far Cry's strong points as a series is the massive improvement between each game. My other hope is that they haven't tried to remake Vaas in the self proclaimed Himalayan king, because although Vaas was one the best villains - nay characters - in any video game, I think we can all agree that taking what made him successful and pasting it straight onto this new guy would ruin it.
But I haven't yet seen evidence of any of those things happening so let's say... cautiously pessimistic.
That said, there are many aspects of FC3 that I wouldn't be at all sad to see in this new one. The cover system, the map design quality, the stealth system (with some improvement) and I suppose the core combat are all things that I would like to see, but there is certainly room for some newness and improvement.