I spent the last day upgrading to Hardy Hedgehog.
The upgrade takes about twelve hours. (I've done it twice, now.) This may speed up when the servers aren't getting hammered, but the second time, I just started it before I went to bed and let it run all night. By the time I got up the next morning, everything left to do (clicking to accept a handful of installation choices) was local.
On the first box, a desktop, tracker crashed and complains. I filed a bug. On my laptop, I turned off the pretty screen-saver because it kept freezing. Also, on the laptop, compiz fusion keeps opening my windows under the panel, so to move them, I have to use Alt-left-click. I filed another bug.
On the good side, the laptop, which I'd had to fuss around with some on Gutsy, just came up and worked. The new default settings are for full, compiz-fusion eye candy, which is nice. I suspect an interaction with the screen-saver to be the "freeze" problem, so I'm willing to live with the trade.
I haven't tried the wireless yet -- maybe it's improved, too. :-)
It all seemed pretty painless.