This is the reason I'm sitting here right now, rather than sitting in the car on my way to buy a new iMac.
I bought a Macbook Pro a couple of years ago and love it, it's by far the best laptop I've ever used.
The time is now here when I want to upgrade my aging desktop PC and based on how much I like the Macbook, an iMac is the obvious choice, but reading these forums I'm having doubts.
I'm currently on a 24" Dell Ultrasharp display and when doing tests, I can see very subtle inconsistancies in colour through the screen which I never notice in day to day use. I think the thing that is frustrating here is that there obviously are perfect displays out there, but there seem to be a lot of people making do because the yellowing on their particular screen "isn't that bad". I don't expect the same kind of quality you'd get with a £5000 Eizo monitor, but I do expect the same kind of quality you'd get with another identical iMac!
If I were looking at stand alone monitors and there were reports of one screen with so many problems, I'd stay well clear, but obviously the iMac has other attractions. I like the OS and I like the way everything works so nicely together, I hate myself for saying this, but it also looks far nicer than any other computer on the market!

That said, I'm not bothered about an all in one device as such, but the MacMini is underpowered for my needs and the MacPro is overkill. I almost wish they had a model inbetween the two so I could just buy that with another display and the issue would go away!
I realise I could return a dodgy screen, but it's pretty awkward having to carry it all back to the Apple store, especially if I find (as some people do) that the replacement is just as bad (or worse!)
So, I suppose I'd love to know if this issue is as widespread as it seems from these forums? I realise people are far more likely to leave comments online when they have a problem with something than if they're happy with it. Are bad screens relatively rare, or are lots of people just 'making do'?
I'd very much like an iMac, but I hate the thought that one of the most expensive things in my house isn't working as it's supposed to.