I'm really interested in the co-op, which looks like a completely different game. And if they've learnt from the mistakes of Far Cry 2 for singleplayer then it's going to be awesome. The videos they've shown so far haven't looked that impressive but I think that's because they from the console version, especially if they're recommending such high-end specs. Far Cry 2 had awesome graphics and was incredibly well optimised - I thought it was much better than Crysis in every way. If Far Cry 3 is as well done on the PC then I'll be very happy.
I'm glad that Ubisoft has gotten rid of the online DRM requirement, though I still want to know whether it has limited activations. I skipped on Anno 2070 because of the Tages 3-machine activation bullshit. After being locked out of Crysis 2 and STALKER: Clear Sky I can safely say that limited activations are retarded and only hurt legitimate customers, as pirates have working cracks within a day or two.