Ive played with it, I used yellowdog linux, some things for the G5's still doesnt work, like fan speed control for the cpu fans, they are either on full speed or off, not sure if theyve fixed that yet, I hooked mine to a 3 position switch a a resistor so I had off, 1/2 speed, and full.
Dual boot, dunno, booting on apple is different, I used single boot only.
Performance wise, well, in some ways it was better, in some ways it wasnt, linux doesnt have aqua or carbon or cocoa so you dont have all the graphics layers and API's to bog the system down with RAM and system call requirements.Its gonna be fast anyway, G5's have lots of horsepower to begin with. Yes nvidia cards for mac are different I do believe and mac drivers arent available for linux so you have to use a framebuffer as far as I know, which is what I did, which means no 3d acceleration at all. Which is fine really, it works. thats what im using now with integrated unichrome graphics on my box. You can do movie playback and most other things just fine, just no openGL,DRI, or GLX acceleration. Although DRI can be done as of a few weeks ago, that project has been coming along pretty well.
The PPC kernel has firewire working, dont think blutooth is working yet, they may have gotten the fan control working, dont know, check the yellowdog website or PPC linux sites.
To be honest, and I might get flamed for it, but while fast in its own right, the PPC chips arent all that really, any of the high end intel or amd chips kick its ass anymore.They are cheaper and faster.While big endian and altivec has its advantages, the intel and AMD's have serious serious thruput and bandwidth these days, it makes up for not being 64 bit and having as many registers.
slick and easy to set up, NO, NOT AT ALL, doable yes, fun to play with yes, practical for everyday use, well, not really, there's like no drivers for much of anything, usb works, so most business class printers will work, but not all linux apps can be cross compiled for PPC, most can, some cant