Julia, I can completely understand where you are coming from and even have to agree with you in some respects.  I love Sophie Kinsella's style of writing and will read anything she writes under that name because of it, however, I do have to admit that I wish she'd left the Shopaholic Series alone after the first three books as I do think they went downhill a little after that.  I don't think they're terrible by any means of the word but I do think that they kind of lost their edge.  I much prefer her standalone books!