Happy with it.
I'm a graphic designer in the market for a 27 inch iMac and the specs looks great for what I will use it for. I'm not a desktop gamer and I'm not after the most powerful computer in the world. What the new iMac offers me is basically all I need - the thin design looks great, but its not at all important in my decision to buy it.
I think a lot of the moaners on here maybe miss the point of the iMac. It is the workhorse of the design industry. Every design studio or office I've ever been in use iMacs or Mac Pros. Apple will be fully aware of this and will definitely tailor their iMacs to lucrative markets such as this rather than the casual home user/gamer etc.
Get the option with the turbo boost to 3.9GHz. Adobe will love you for it.