Whether or not Sisters is the best use of Fey's or Poehler's gifts is beside the point; they're entitled to blow off the same dopey steam that propels the likes of Robert De Niro and Blythe Danner in all those Fockers movies.

Pell's script, inspired in no small way by her own relationship with her own sister, is so smart, so genuine, as crazy as things might get the human saga at the center remains pure and realistically heartfelt no matter what.

Is Sisters a good movie? No. No, it is not. Its plot manages to be both jarring (so many twists!) and predictable; its supporting characters are thin; it makes gleeful use of tired stereotypes.

Even a go-for-broke, R-rated potty-mouthed jolt from two of our favorite, and normally buttoned-up, comediennes can't save this film.