I've liked Arquette before, though she's not nearly as prolific as her sister Rosanna. I guess you could say she's also not as memorable; Rosanna is more obviously Rosanna in many of her roles, whereas Patricia, more of a character actor, sometimes fades into the background.
Maybe I'll give "Medium" another chance later this season, if it survives.
Meantime, I'm hooked on "Lost," thanks to Joy wanting to watch it while she was in town.