They completely killed the characters!
Okay, I don't need to say that I didn't like this adaption at all, because that's obvious.
I'm not blaming the actors and actresses, since they only did what they were told, but the writing and the acting destroyed T*Witches for me. Beth was especially bad. In the book, she was feisty and much more likeable than in the film. In the film, she's just completely stupid with an annoying voice. The twins too, they were more serious in the books and a lot more mature, not to mention they were supposed to be 14, not 21. There was also more interaction between the twins before they realised they were witches.
The characters were all ruined, except maybe Lucinda. I didn't find her that bad, but Beth? I just wanted to break the TV.