I don't remember if I said this already, but it'd probably take longer to look through 6 pages than to re-type it anyways. My 30 gig 5.5 gen suffered from heat stroke (left in glove box with windows closed in the sun on 100+ degree day), and the DAC out pin from the DSP managed to lift itself off the board. I gave it to a friend who had the tools to fix it, and two months later, after it still wasn't fixed, I bought my 80 gig 6th gen.
You can clearly tell that they put a significantly faster processor in it, and did a lot to the UI. It has cover flow, and it's less choppy than it is on my macbook! My only complaint is that the screensaver is boring - it shows play/lock/battery/clock status in black and white; it should use the cover art thing from the main menu.
It also exhibits some weird behavior when it's tethered - under certain circumstances, it forgets that it's tethered and goes back to the main menu (as long as you're not accessing the disk). That may be the intended behavior, but I don't think so because my 5.5 gen never did that.