I liked the little extras to the story...*spoiler*
....but the plot was a little TOO busy. Way too many plot devices to keep track of!
And it dragged on a bit too long, I thought. The wife and husband's "I didn't sleep with her/Yes you did' thing got a bit old after a while.
But the acting was very good, better than in its American similarly-themed film "The Hand That Rocks the Cradle".
As horribly evil as Fiona was, she managed to make one feel a tiny thread of sympathy for her in some scenes. That's hard to manage for the villain; I didn't feel a bit sorry for Rebecca DeMornay's character in the American film.
That said, I cheered when Fiona FINALLY got a comeuppance of sorts (I thought it would never happen!). She had no right at all to try and destroy the family of a woman who trusted her.
It seemed to me that the wife trusted Fiona awfully quickly. She barely knew her!
"I'd say this cloud is Cumulo Nimbus."
"Didn't he discover America?"
"Penfold, shush."