The Haswell CPU represents a "tock" in Intel's "tick-tock" development program. A "tock" represents a new microarchitecture whereas a "tick" is the shrinking of the process technology.
So what does it mean for you?
One of the main benefits of the Haswell CPU appears to be a longer battery life. There are 3 modes of operation: Awake, Sleep and Awake Inactive as opposed to the two modes of the Previous Sandy and Ivy Bridge Processors. The smaller size of the Haswell chip will support the decreasing size of notebooks and tablets.
There is also a significant performance increase over 3rd generation "I" processors, especially for gaming in systems that don't have a dedicated graphics card.
However, there is concern from the community that the Haswell represents Intel's focus on tablets and notebooks due to it's emphasis on small size and small power. Nevertheless, on paper the Haswell is still a more powerful processor, but time will tell whether it is the more cost-efficient CPU for a desktop gaming system.
One interesting thing I noticed on the Intel website is a claim that you can run "modern" games with the Haswell integrated graphics, without the need for a dedicated graphics card. Behind this claim is an image of Battlefield 3. The idea that you could play Battlefield 3 without a dedicated graphics card and get even +20fps on an integrated graphics system is a pretty extreme claim .
Going to have to call BS on that one.
Take a look for yourselves: http://www.intel.com/content/www/us/en/benchmarks/laptop/4th-gen-core-i7-4930mx-4950hq.html