We have mentioned a few details about Skylake-S including the fact that it comes in 35W to 95W TDP envelopes, that there will be unlocked version and it will need a 100-series chipset to work.
The added DDR3L/DDR4 supporting platform might make it faster and/or more efficient. It looks like Skylake-S has the power to make hardware speech acceleration do time synchronization in hardware. You can expect support for Intel Ready Mode Technology, Intel Device Protection Technology with Boot Guard, Intel Memory Protection Extensions and Intel Software Guard Extensions implemented in this new LGA1151 core.
There is an indication that Intel might abandon FIVR (Fully integrated voltage regulator), a feature that was a big item in the Haswell architecture. Maybe the fact that there are two different memory standards to deal with (DDR4 and DDR3L) contributed to the decision, but we don’t know this for a fact.
It will be interesting to see Skylake-S (Desktop LGA version ed. ) and Broadwell desktop parts coexisting and launching roughly at the same time in Q2 2015. This never happened to intel before and launching ‘tick’ and ‘tock’ parts at the same time is an unusual decision for the chipmaker.
Until that time comes Haswell refresh Core i7 4790K remains the fastest premium CPU that is not a part of the Extreme Edition family.