I have to admit that the new iMac is gorgeous after seeing the 21 in model in the Apple store earlier today. Sadly, though, I won't be buying one for several reasons and I waited 6 months for the new ones to show up to replace my 3rd iMac an early 2006 model.
The new iMac is honestly disappointing in many ways.
1) Fused case means if something goes wrong it can't be fixed and the whole machine has to be replaced (and that includes the 27 in model which has an access door only big enough to upgrade ram).
2) the 640M graphic card in the base model is out of date on arrival. The 650M in the top end 21 has limited future functionality due to having only 512 mb (a concern for gamers etc or those like me who tend to keep computers for lengthy periods of time)
3) All of which forces you to spend big bucks on the higher end 27 in models which are really more money and screen then I, and many others, need or can afford.
I was going to buy an upgraded 21 in and a portable but the limitations imposed by the spec structure killed that idea. Didn't want to spend $1500 on the top end 21in iMac and $12-1500 on a 13 in air or cMBP and not have a computer with good enough graphic options to play new games a year or 2 down the road.
So, anyway, needing a new personal computer and a portable for work, I opted for a middle of the road 15 in cMBP with the added benefitted of an optical drive and increased serviceability. It also has the 650M but with 1 gb.
For me, the end of a 10 + year relationship with iMac is a sad day.