As outlined by Maury over at RailheadDesign, the Network Proxy Icon in the "Connect To" dialog box. (
www.railheaddesign.com). That's the only "glaring" problem I've seen in 5G64, and it's not major and can be easily fixed probably with a quick update through the Software Update System Preference. Maybe it's fixed in the build that went to manufacturing, and is such a minor cosmetic glitch that Apple didn't warranty giving it a higher build # (which happens)...
As to the Printer Support. Epson did say that they would have additional printers supported with the release of 10.1, but they didn't necessarily state that Apple would be delivering them. From what I understand, the next batch of drivers is going to come from Epson directly, instead of through Apple, so them not being on the disk that Apple sends out doesn't alarm me.
5G64 rocks, period. I've already installed it on all three of my Macs, and don't really see much need for 9.2 anymore. I can now burn data and music from 10.1, I can finally access my SanDisk Imagemate and retrieve my photos, I can watch DVDs, and Classic is just as fast (if not faster) than booting in to 9 directly.
With 10.1, the OS itself is removed from the equation of people holding back to upgrade to it. Now the only major impediments are native applications (for those whose app won't run in Classic due to hardware support), and drivers. With 10.1 here now, but of those problems will start to subside over the next couple of months.