Amnesia is tricky. It's very easy for it to come across as either dated or corny, backed by inaccurate or hand-wavey medical science. Its popularity as a plot device peaked in back in about the mid-1970's, and the "oh my God it's all coming back to me!" revelatory scene is now as clichéd as the villain who discloses his entire plan to a captive James Bond. Very, very tricky, and it's a brave writer who ventures into this territory.
Fortunately, Sophie Kinsella is a brave writer, and a good one, too. Yes, the protagonist had an enormous gap in her memory, and yes the person she wakes up as is different in pretty much every way from the person she remembers being - different hair, teeth, body, job, home, boyfriend (well, husband), wardrobe, priorities, you name it - but the difference here is that, under the gloss of the fully automatic Kensington loft-style flat, impressive job title, and gorgeous rich husband, Lexi is unable to account for the changes in her life. Information slowly trickles in, and she begins to understand how things changed, but the why continues to elude her. And it's the why that's interesting, that keeps the reader intrigued. Because what could possibly inspire a mid-twenties fun-loving working girl to turn into a hard-nosed boss bitch from hell who alienates her closest friends and sublimates her own tastes and desires and nature to live a life that looks dreamy from a distance, but doesn't feel like her, up close?
Some of the characters are brilliantly drawn, especially Lexi's mother, who proves much more sympathetic than I ever expected. I wish she'd had a bit more screen time. Same with younger sister Amy, who had great potential, and Lexi's dad, who is dead before the story starts, but has a lot to do with the why.