I read the first Shopaholic book in February before the film came out in theaters and enjoyed it greatly, though it didn't hook me enough to keep me reading until a friend lent me the rest of the series this summer. While some series' get worse as the books progress this series just got better.
Confessions of a Shopaholic is the first of the series, introducing the readers to Becky Bloomwood and her shopaholic ways. It also introduces the reader to a cast of fascinating characters including her parents, her best friend Suze, Suze's cousin Tarquin and, of course, the love interest, Luke Brandon. While the book is funny as she gets herself into trouble because of her shopping habits halfway through it's evident that the story needs some sort of meaningful resolution to be a completely satisfying book.
Shopaholic Takes Manhattan was my least favorite of the series. It's a repeat of the first, set in Manhattan, with higher stakes.
Shopaholic Ties the Knot is when the series really starts to glow. Becky and Luke are engaged but she's in a bit of scrape: both her mother and his are planning completely different weddings and she doesn't know how to say no to one of them.
Shopaholic & Sister finds Becky being introduced to her long-lost sister. But as she tries to bond she discovers something terrible... her sister doesn't like to shop!
Shopaholic & Baby follows Becky as she's pregnant. When she starts seeing the it obstetrician of the stars she discovers that the woman is Luke's ex and suddenly she's afraid that her marriage is falling apart.
Overall, while the first two were fun the last three had lots of heart. They were still entertaining and she was still a Shopaholic but the story no longer focused on her shopping escapades and debt alone. They focused on her relationship with Luke and her friendships, which I found to be the heart of the story. I'd love to read the first again, to go through the beginning of her relationship with Luke once more but the last three I could read many more times.