Hey,
Its actually not the widest FX zoom, that honor goes to the Sigma 12-24 F4.5-5.6, which has more problems with flaring, haloes and chromatic abberations, but is still a pretty nice lens, and a darn sight cheaper than the 1500-2000 price on a 14-24 F2.8 (good luck finding one for under about 1900 atm since the Japanese earthquake)
Ive found it pretty good with flare, certainly better than any other UWA i've tried. I've been running a heap of tests and tbh I don't know what people are complaining about. Relative to some of the lesser offerings I find on a crop frame I think its really not that much of an issue, completely smashes a sigma 10mm on a crop frame. Its probably just a case of people whining because they are looking for something to be wrong with the lens. Alot of people get too hung up on minor points and end up not using gear because of it, when in fact if a bit of care is taken you can generally avoid/minimise the problem. Same thing with the weight of the lens, people whine and whinge about it but realistically its not that different to any other decent bit of glass and balances well on an FX or DX body. I find the 24-70 feels more ungainly/heavy purely because the 14-24 has its weight distributed closer to the body, even though its notionally lighter.

I haven't had mine for that long, but have rented it to try in the past and not found it an issue compared to what the lens provides. And I can honestly say I only wish I had this lens earlier. Its unbelieveable. Blows everything else out of the water. Sure it takes a bit of skill to handle and control like any lens (and perhaps moreso as its a bit of a specialist) but the IQ it gives corner to corner wide open and throughout its range is better than the primes for a reason. Ill be interested to see if flaring becomes a problem while shooting storms for 6 weeks in the states, but I somehow doubt it will be.

Hope that helps .