Update!
I have now had a few hours to play with my new computer and here's my take on it...
First off, I absolutely love it. I debated for a while over getting the 20" or the 24" screen and had a hard time making up my mind. Macrumors members finally talked me into the 24" and I couldn't be happier! Just as most people said, it looked somewhat large when I first took it out of the box and set it up. It took a little bit to get used to. The extra screen real estate on the larger monitor is such a luxury. To be able to browse the web and have a few iChat sessions going on at the same time on the same screen is so nice.
The screen is very bright. I felt like I was going to get some sort of sunburn if I say in front of this thing too long last night! Turning down the screen brightness is going to be a common occurrence when working on the computer at night. The resolution is outstanding and I will confirm that the viewing angles are great! There is next to no color shift for most viewing angles (confirmation that it isn't a TN film monitor). The corners do experience some SLIGHT darkening and there is a very minimal backlight bleed when the screen is completely black. Again, it is VERY MINIMAL to the point of no concern or annoyance at all. Lastly, no dead pixels.
Screen reflection. Here we go on this topic. I realize it bothers some people and I don't want to start a 20th argument on this thread about it. However, for me, it doesn't bother me even the slightest bit. I totally even forgot about the whole screen reflection until late last night that I remembered I should be looking for it. Even then, with a lamp on behind me it was very minimal and only when I focused on it. This screen is just so bright that it drowns out much interference. It's pretty much like watching a reflective television, however, I think my television might even be a little worse---even then it doesn't pose any sorts of problems. Overall, the glass panel really brings out the colors on the screen. It simply looks amazing.
I watched a movie last night on the iMac. The quality was WONDERFUL. Even viewing this baby from a distance is a pleasure. Connecting external speakers is really the way to go. The quality can be great beyond those internal speakers. I will say that they are better than laptop speakers, but they are still internal screen speakers and perform as that. They are certainly better than nothing though.
A few people have expressed concern about the heat issues. So far, mine has been hot to the touch near the top. It hasn't been too hot as to not be able to hold my hand on it for an extended period of time. It's best to keep in mind, however, that this aluminum will dissipate heat MUCH easier than plastic so it's expected to be warmer (this is, obviously, a good thing). According to iStat, here are some numbers right now (I am doing no intensive work right now, so this is more of an idle temperature).
94% Idle
GPU A - 106
GPU - 133
GPU Diode - 133
GPU Heatsink - 131
Ambient - 76
Memory Control - 119
HD Bay 1 - 126
Optical Drive - 112
FANS
Optical Drive - 699 rpm
CPU Fan - 1206 rpm
Hard Drive - 1200 rpm
The keyboard, up to the point, has been absolutely wonderful. Although I'm very used to typing on a laptop, this keyboard still has a different feel. It's going to take a little getting used to, however, I'm loving it so far! I purchased the wired version as I wanted a number pad.
I have Aperture and iWork '08 but really havn't gotten to use either to their full potential. Once I do, I can answer any questions on their performance. I need to go get myself a good CompactFlash card reader to speed up the transfer process of my RAW photos.
Sorry this is not TOTALLY detailed, however, I'm just getting started with the whole experience. For those of you on the fence between the 20 and 24...if you think you've got the room, then DO IT. It will certainly be worth it.
Pictures coming...
That's all I have to say about this beauty! I have yet to turn it on and play with it. I am on lunch and if I turned it on, I'm afraid I wouldn't go back to work 
