I cannot say much about the chip set, but now that CES 2013 has happened we have more information about the processor. The processor itself is nothing spectacular with regards to performance gains. It will be 5-10% faster. To expect more would simply be lying to yourself (although we can dream can't we?). What will really has changed is the power consumption and the on board graphics. Graphics performance will likely be on par with a GT 650M (Source Here). It seems like Intel is trying to get rid of the sub $100-$150 discreet graphics cards. The other big benefit is power consumption. Rumors are flying about all day battery life on some ultra books. In fact, Intel specifies that an ultra book based on Haswell will have 9 hour battery life (Source Here). They get better performance with lower power consumption in a number of ways (Source Here). All in all, you will only see benefits in some specific CPU heavy situations. Video encoding, rendering and so forth. For gaming, no real difference. Also, you will see a difference in power consumption. Battery life in laptops will likely shoot through the roof.
I'll do a bit more research into the z87 chip set and let you know what I scrounge up. Until then...bump.