1:New Biaxial carbon deck, so not as fragile, and slightly better at absorbing chop.
2:New cut out for less drag/more speed.
3:Pinched in tail at the OFO for free'er feel.
kvda, I'm still on my 2011 iS107 for this year (cause I love it)
but reading between the lines, I would guess that 2 and 3 will mean you use a fin that is that is more top-end biased than the 2011. BD and Benny used the iS107's in some fairly high-ish winds last year, so would make sense to improve the top-end performance instead of the low-end performance, especially as the iS117 wide and iS127 are doing so well in the low-end conditions.
A good price on the 2011 iS107 would be good choice I guess. Not the official line, just me guessing