I have to admit that I was surprised to find that the author is not, indeed, a teenage girl. Okay, I'm joking a little bit, but to me, the "voice" did a good job of conveying the thoughts and attitudes of young girls, to the point where I found myself, as an adult, getting somewhat annoyed with them.
I think this would be better for a young adult audience; perhaps that was the intent, but the description was fairly short.
I found the mother to be somewhat over the top. I wouldn't really expect Cecile to be a reliable narrator when it comes to her mother (what teenage girl is?), but the actions we're allowed to see objectively were not, in my opinion, believable. The idea of a mother discussing childhood issues in economic terms is somewhat amusing, but when taken to the point of asking a 5-year-old to justify a trip to McDonald's in such terms, it becomes almost a caricature. Repeatedly encouraging her daughter to think about the future is believable and consistent; the extreme steps taken by the mother in that effort were not, at least to me.
The premise itself is fun and although my adult perspective meant that it was a bit difficult to suspend disbelief in spots, I was able to run with the story, for the most part. The utter determination shown in the face of challenge after challenge was both amusing and...well, I can't say it was "inspiring" for me as an adult, but I thought it did a good job of showing that maybe one can't accomplish exactly what one sets out to do, but one can certainly do *something* worthwhile. Even the mother finally redeemed herself a bit at the end.
