I am new to this forum, but I wanted to chime in and let you know of the hands-on experience I just had with both the G5 iMac 1.6G 17", and 20", 1.8 Ghz models.
Just to let you know, I was an apple developer up until the last version of system 9. I changed jobs and they have relegated me to the PC world for the last 3 years. I have been dying to get back to the Mac, and I am at a point where I am ready to buy a new computer.
I currently am doing network and corporate television post production editing, 2D & 3D graphics compositing and animation, as well as a lot of photographic image manipulation on a plain ol' Dell Lattitude C840, 2.4 Ghz Laptop, 1Gig Ram, and nothing else special on it with lots of external firewire drives, tape deck, monitors, speakers, midi keyboards, and USB devices attached. I use Avid Express DV to edit, Photoshop & After Effects, and Maya for my 3D app. I do lots of multi-layered renders in all apps with very acceptable results and time-frames from my laptop PC. This set up has served me quite well for the past 2 years but it is time for an upgrade.
I have been praying that the G5 iMac might be enough of a powerhouse that it could out pace this old boat anchor of a PC laptop, so I would have a good reason to jump ship back to the Apple platform without having to spend $5000 for the minimum set-up of a hi-end G5 dual 2.5G Tower, and still get a reasonable workhorse for under $3 grand, not including software!
So, I spent the last FOUR-AND-A-HALF hours at the Apple Computer store pounding on the newly arrived machines. First, I banged on the 17", 1.6Ghz machine. That only lasted about 10 minutes when I realized that it took at least two minutes just to open Final cut Pro HD. I quickly went to the "Cadillac" of the line hoping to be much more impressed. it too 1 minute and 45 seconds to open FCP HD on that one. ( I opened the same app on the G4 15" PowerBook sitting across the isle from it and it only took 45 seconds to open!)
Unfortunately, I was very disappointed to report that the 20", G5 1.8Ghz iMac, with 512 Megs of ram didn't fare much better. I am sorry to say that is far from the computer powerhouse I had hoped for. In fact it reminded me of the days when I was running the Mac II x! There is NO real time on this computer. with every click there was a considerable delay before the action happened. Programs opened agonizingly slow... and this was with NO other apps open at the same time. You can forget doing much serious Professional work in Final Cut, After Effects, Motion, or Photoshop. Those programs bog the CPU down incredibly, especially at 300 or 600 dpi in PS, or with more that 3 or for layers in AE or FCP.
I actually couldn't believe how slow these machines were! I went back and tried various tests in various software, again and again, with no improved results. You can expect long, intolerable waiting times, just to open any application!
The Apple sales people on the floor seemed like they were avoiding the G5 iMac table all together. Their only comments were, " It will probably run a LOT fasted if you max it out with 2 GIGS of RAM!)". Hmmmm... I seriously doubt that another 1.5megs of ram, at Apple's exorbitant pricing, is going to speed these slow-movers up enough to make enough difference to justify the enormous cost expenditure . I think they sense and know that there are some serious problems with the public image/hype that has been presented for these new machines that they won't be able to live up to. I now understand why Apple has been so quiet about what these machines can really do!
Sure, if you are just going to use Word, do spreadsheets in Excel, Check your email and surf the web every day, this may be the perfect machine for you. But why pay $$$2-3 grand for just that? Just for the coolness of and all enclosed box? There were plenty of computer newby housewives lined up to buy these machines for home that had been swayed by this mystique. But for those of us that need even moderate computer processing power to accomplish any truly creative work on a professional level, this iMac is whack! (Pardon my poetic license!)
As much as I hate to admit it , I was able to get a bid for a screaming Tower PC, with a 3.6G Pentium 4 w/hyperthreading (virtual Dual processor) Windows XP Pro, 2.5 TERABYTES, yes Terabytes of 7200 rpm storage configured into a mirrored 0+1 RAID , 6 x Firewire 800 ports, 4 firewire400 ports, 8 USB 2.0 ports, all the legacy ports you could want, even a FLOPPY Drive!, a top of the line ATI or Radeon Graphics card, digital 7.1 audio I/O, analog stereo I/O, gigabit Ethernet, a 56k modem, TWO DVD+-RW DUAL Layer drives, a wireless keyboard and mouse, and a 21" wide screen flat-panel monitor.
The bid came out to be close enough in price to the high-end fully loaded 20" iMac G5, that in the "more-bang-for-the- buck" category there is just no comparison between the two. AND I get so much more productivity from the PC's processing power that I could EVER get from this sad little iMac, let alone, even the higher end Mac Dual G5 2.2Ghz tower! >

I am truly bummed!
Apple....what were you thinking! I though you were the computer for the REST of US!!!
Back to my PC to get some work done!