I think the biggest issue that people are not happy with the IB is the temp, as people were expecting with 32nm process going onto 22nm, it should be cooler than SB...but the result is actually the opposite.
Granted IB at 4.5GHz is around as fast as SB at 4.7-4.8GHz, but the thing is it is not cooler running than it. Comparing to a new £170 3570K, people can get a (new/2nd hand) 2500K off auction site for £120~£130, so the price difference is quite tempting, especially considering that it is not actually much slower when comparing overclock to overclock and temp.