Clean Break definitely has some likeable aspects about it, and Jacqueline Wilson is a master at really conveying the thoughts and emotions of a child experiencing a parental breakup. I do however think this is one of her poorer attempts, especially in terms of plot and characterisation.
I felt sympathetic towards the character of Emily, who had esteem issues in terms of her weight and how she wasn't the dad's 'real' daughter. This was handled effectively, but for some reason I found the other characters, particularly the mum, to be self-absorbed and at times, aggravating. The gran was the only character I somewhat took to as she was the realist of the family and, however harsh it may seem, gave the family a dose of the truth about the unfaithful father. Additionally... *spoilers coming* after flitting from woman to woman the father returns at long last on Christmas Day and they seemingly live happily ever after. I know this is a children's book and all children's stories should have happy endings, but I felt this was a bit misleading for children who are experiencing divorce or the like for real. 'The Suitcase Kid' was much more realistic in handling such a topic and still managed to do so in a charming and bittersweet manner. It seemed to me the family were prepared to take the father back regardless of his affairs and who was more than likely going to cheat again. This to me made the characters very weak and the overall premise of the book pointless.
Another aspect I disliked, as another reviewer as pointed out, was the whole 'Jenna Williams' thing. I too found it cringeworthy, but maybe it's because I was a teenager when I read this book. There was just something very silly and even somewhat self-centered about it. There was also no real plot; the only climactic moment was Emily meeting her favourite author, spotting the dad in the same shopping centre and breaking her arm, which ultimately brings him back to the family. The main bulk of the book is just the goings-on of the family while the dad is playing away; the mum pining, the two younger children constantly whinging, the gran getting cross and Emily dreaming of the dad's return and writing stories about a reindeer glove puppet. It's nice to read on a rainy day but don't expect anything too stimulating.
Overall I give the book 3 stars, as it does evoke a degree of sympathy, and there are even bits which made me laugh out loud. It has its charming elements and is very Jacqueline Wilson-esque, but as I said earlier, I don't think by any means it is one of her best books.