The folks over at iFixit have done their usual job of tearing exciting new bits of technology to pieces, this time with the new Retina iMac as their unlucky victim. Conclusion: apart from that pretty new screen, everything's more or less the same.
Overall, they found that once you take a scalpel to the edge of the display, you find the same SSD, logic board and memory units hiding under the hood. Of course, as Apple pointed out last night, the processor, GPU and display controller are all new, so that the internals don't shudder to a halt under the processing load of that 5K display.
The most important reveal, however, is that the new iMac keeps the rear-access panel that makes the RAM user-upgradeable. That's welcome news for anyone who doesn't want to pay the price for Apple to upgrade their RAM, or perhaps wants more than the 32GB allowable by Apple's config machine.
If you have a hankering to upgrade any of the other components, iFixit found that the processor, GPU and SSD are all upgradeable, assuming that you're comfortable with taking the screen off, a process that involves cutting and then replacing Apple's special double-sided tape. For that reason, iFixit gave the Retina iMac a repairability score of 5 out of 10: not the easiest to fix, thanks to the fairly complicated screen removal process; but at least almost everything is replaceable without sending the whole unit back to Apple. [iFixit]