Final words: "Im a fan of Haswell, even on the desktop. The performance gains over Ivy Bridge depend on workload, but in general youre looking at low single digits to just under 20%."
http://www.anandtech.com/show/7003/the-haswell-review-intel-core-i74770k-i54560k-tested/9
http://www.anandtech.com/show/7003/the-haswell-review-intel-core-i74770k-i54560k-tested/9