Jennifer Reese of the American magazine Entertainment Weekly praised the book, writing that "while The Accidental does not add up to much more than a clever stunt, Smith pulls it off with terrific pizzazz.

Through each character we obtain a different view of how Amber came into their lives, and who they believed her to be, when she arrived unannounced and uninvited at their Norfolk holiday home, claiming her car had broken down.

Through "The Beginning", we learn of Astrid's obsession with video-taping her life, seemingly as proof it existed; of Magnus' involvement in a school prank which resulted in the suicide of one of his classmates; of Michael's affairs with his students (he is a university lecturer); and of Eve's writer's block.

"The Middle" deals, again, with each of the family members' experiences of Amber: she throws Astrid's camera off a bridge into the road, she seduces Magnus, and reveals flaws in Eve and Michael's relationship.

The house has been emptied of all possessions – we must assume, as the family do, by Amber – leaving nothing but the answering machine, which contains messages forcing Magnus, Michael and Eve to face up to their past.

[9] He notes also the intertextual and "intergeneric" nature of the book, the way in which it references the Italian director Pier Paolo Pasolini's 1968 film Teorema in which, likewise, "a mysterious, beautiful stranger [...] arrives from nowhere into a family and, simply by virtue of what he is, destroys their merely 'theoretic' coherence".

[10] On the March/April 2006 issue of Bookmarks, the book received a (4.0 out of 5) with the critical summary saying, "Most reviewers echo Stephanie Zacharek in Newsday: "Even if she’s just a metaphor, she’s more human than some of the ‘real’ characters you find in contemporary literary fiction".

[14] Gail Caldwell of The Boston Globe called it a "thoroughly charming and melodic novel," adding that it was "small and glistening, one confident little shooting star instead of a cumbersome light show.

"[15] Adam Begley of The New York Observer called it "A delightful book," adding that it is "a satire that's playful but not cuddly, tart but not bitter, thoughtful but not heavy.

"[16] Michael Schaub of San Francisco Chronicle wrote "as dark as the novel can be, there are genuinely funny moments as well," adding that "the last sentence of the book manages to be enlightening, confusing and almost destructive in its simple power.

Club praised the book, commenting that "though The Accidental is more spectacularly messy than brilliant, it has a strong perspective on what it means to be alive in the early '00s, and constantly tugged at by the disturbingly similar feelings of guilt and self-righteousness.