So far, the honours are about evenly divided. The wireless LAN isn’t reliable under XP (even with power-saving disabled for it), and the power management (speedstep, suspend-to-RAM) doesn’t work (yet) under Linux. Except that the CPU fan never comes on under XP; I’m assured by TwinHead that management of this fan is a hardware function, so I suspect that the speedstepness is jammed at less than full blast.
Update: XP just failed a resume as well (laptop woke up to a black screen, and the hard disk flashing every few seconds... forever...). Only once, so far, but it does make me wonder why this whole ACPI thing needs to be so complicated and dodgy.