I think this post best illustrates why a lot of people are not thrilled with the latest update:
I share your apprehension (about the new liquid cooling system). The presence of the Rev A Liquid Cooling technology deployment will be the number 1 reason why I don't get a 2.5 - if I don't.
. . . Together with the disappointment I feel over no second optical drive bay, no additional hard drive bays, and this initial-deployment of a new cooling system (given the sporatic performance of many of Apple's Rev A introductions), I'm generally not thrilled at all with this increment.
Notice, he's not saying the new cooling system won't work -- just that it is a "rev. a" change to a "rev. b" machine -- and that no other obvious improvements have been made.
EDIT: I found another post that reinforces my feelings of disappointment about this update.
June 12th, 2004 -- I spent yesterday testing the Rev B G5/2.0GHz MP Power Mac. Some early impressions and insights:
1. The GeForceFX 5200 is wimpy. (I've added its 3D numbers to the Radeon 9800 Special Edition article.) If you plan to run any OpenGL aware apps, you should special order your G5 and specify the $50 for the Radeon 9600 XT (128M).
2. I'm not sure if the 2GHz "Rev B" G5 uses the 90nm chip, but it is not any faster than the 2GHz "Rev A" G5. I ran the iMovie effects render test, Cinebench 2003, and Xbench. Virtually identical results. (Xbench identifies the "Rev B" as "PowerMac7,3." The Rev A is identified as a "PowerMac7,2." Isn't the 90nm chip supposed to be identified as a "PowerMac8,1"?)
3. The FireWire 800 RAID write speed issue has NOT been fixed. In my quick test with a striped pair of LaCie Big Disk Extremes on the built-in FW800 port, the sustained write speed is still stuck at 54MB/s while the same pair connected to a G4 PowerBook gave a sustained WRITE speed of 74MB/s. (A PowerBook beats a G5? Huh?)
I admit that the new top end machine is very interesting -- but I always buy the mid-price point. And to date, these machines are not attractive to me until they fix the known problems (including the power supply).