I upgraded few days ago and ran into problems
my wireless card based on atheros chip stopped working
it seems they’ve deliberatly removed madwifi support from wpasupplicant or something so I did two things, I downgraded wpasupplicant to hardy version and compiled/installed madwifi drivers from the project website
another problem that is still unresolved is the graphics
they’ve removed the old good driver, i810 and instead put intel driver for xorg
the intel driver is twice slower
I can’t watch flash movies any more, it’s that slow
and worse, if I hibernate from the X, I get garbled screen on next startup, nothing works
so I’ve found a workaround, I hibernate from text mode 
anyway, I noticed kde applications have better looking interface, a new sound manager (pulseaudio), no more gaim (now it’s called pidgin)…