I'm more interested in the Z170 chipset than the SkyLake CPU, although I'm sure I'll be able to put to good use, the new features of Skylake, and will enjoy the lower power consumption.
Haswell, and the Z97 chipset had 16 PCIe3 lanes from the CPU, and 8 PCIe2 lanes from the Z97 chipset.
Z170 has 16 PCIe3 lanes from the CPU, and 20 PCIe3 lanes from the Z170 chipset. That's quite a large update. Especially if your a storage freak.
Unfortunately, Skylake requires (in all top end boards) DDR4 RAM, so this is going to be an expensive upgrade.