Right now with the very latest Intel Linux graphics driver, the Core i7 4770K "Haswell" is generally 12~20% faster than the Core i7 3770K "Ivy Bridge" CPU. However, for the id Tech 4 games in particular, the HD Graphics 4600 actually comes up short. The Intel Linux graphics driver for Haswell is still a work-in-progress and it will likely be a few months before things are in order with -- hopefully -- competition to the Haswell Windows driver.
Among the other Haswell Linux articles coming up on Phoronix will be a new Intel Windows vs. Linux OpenGL driver comparison. The Linux 3.10 + Mesa 9.2 driver configuration is already much faster for Haswell than what's shipped in Ubuntu 13.04 by default with Linux 3.8 + Mesa 9.1, as will also be illustrated in a separate article. Stay tuned for more Haswell Linux articles in the coming days on Phoronix.
So far in my testing of the Core i7 4770K in the past few weeks, I'm confident in the CPU and the Haswell architecture although it's clear the Linux support still has much polishing ahead.