I'm not going to buy one now - I have a mac pro and two monitors (Both IPS) already, but I imagine that for anybody who does buy it, the reasons would be the same as always. Professionals will probably wait for specs before they buy:
IPS Panel (if it has it; I suspect it does) - with LED backlight, better gamut fewer backlight problems. No dimming/warm up problems. Glossy aside, might have potential use for people who need accurate monitors. The old ACDs are best known for SWOP matching, especially out of the box. We'll see how these do.
Convenience - if you've got one of the new Macbooks, or are a photographer, say, doing tethered shoting at a studio, this is pretty quick to set up, wire-wise.
Style - lots of people are willing to cough up big dough for this.
For my part, I wonder about the specs. I suspect that if it doesn't turn out too well color-wise, not too many people who don't really want the style or convenience will bother with this one. As it is, nobody can connect it to their mac pro, immediately removing the largest market segment for people who bought the previous displays. Which remain on sale at the same price, so they may actually just be adding a smaller product line rather than replacing a product. Given how much laptop sales are up, this actually makes sense since their market for the "old" ACDs is a small core, mostly professionals, that isn't going to change any time soon. And those people are equally likely to buy a NEC or Eizo display, anyway.
As for the "ton of money" argument, when was the last time you saw a truly cheap IPS panel? The cheapest 24" IPS panel monitors start at $600, for an HP or Doublesight. Believe it or not, Apple's display occupies the medium price in the range here, or if you're looking purely at high end/professional use LCDs, it's actually "cheap". Most people, particularly the ones complaining about prices of ACDs, aren't the intended market. If they have to ask why it's expensive - or why an IPS - they oughtn't be buying one. That said, I cheaped out on my monitors by buying a Doublesight DS-263N and a used NEC 2090UXi, but I'm a student. My equipment isn't (yet) being provided by a company with deep pockets.
Hope that clears some of this up. The LCD question comes up time and time again, though I will admit that right now, it's a bit confusing. Wait for the dust to settle. We'll see what the specs look like. Right now, probably a new IPS.
