The PowerMacintosh G3 AIO is unique in one thing: is the heaviest Macintosh ever produced by Apple. That thing is a behemoth, so shipping is usually more expensive than the computer itself nowadays. 60lb, aprox. 27kg. And it's also quite big.
It was only released as an education Mac (as far as I know, I might be wrong on that one) and it was the first desktop Mac to feature translucent plastic in its design, and the last Apple AIO with an expansion (PCI) slot, an ADB port, a floppy or SCSI disk drive, an Old World ROM or a beige design. Kind of the last one of the original AIO line of Apple, the iMac was completely different to anything released before so I wouldn't consider it an evolution of previous models.
Also, it had not one but THREE PCI slots and a weird PERCH slot only used for early G3 Macintoshes, and a bigger power supply to feed those slots, up to 300W vs the 80W of the original iMac.
It wasn't on the market for a long time, and as the iMac was released and it took all the attention and the PM G3 AIO was discontinued. I don't know about anyone specifically interested in this model.