What isn't mentioned is that alot of games won't take full advantage your CPU so the extra cores aren't actually that useful unless your for instance gaming then running programs in the background such as streaming or screen capture software. Though this is a big mention alot of newer games are really leveraging more CPUs so the AMD are actually starting to edge ahead due to increased utilization of these extra cores. And then ofcourse new gaming consoles so xbox one and ps4 use a AMD 8 core processor so games will be really starting to utilize all these cores so you could be shooting yourself in the foot getting a 4 core i5 haswell chip. You may be alot safer getting the AMD fx 8350.
As well AMD and intel are competitors so each time they produce a chip set it is designed to beat their previous competitors so AMD fx8350 was released before the haswell chipset so in theory the new haswell should beat the AMD (basically they are always leap frogging each other). Another thing to mention the haswell chipset does get hot like very hot, but its now more stable at these higher temperatures (This is being said by alot of people on the internet).With the new i5 running hotter it has sacrificed some of the overclocking potential.
If your building a Rig with a new Haswell chip i5 the price with a FX 8350 are actually pretty similarly priced
here are some links for performance.
http://www.cpubenchmark.net/cpu.php?cpu=Intel+Core+i5-4670K+%40+3.40GHz&id=1921
http://www.cpubenchmark.net/cpu.php?cpu=AMD+FX-8350+Eight-Core&id=1780