I don't mind Sonia, or rather, I didn't until they started turning her into Dot. Dot being the Square matriarch worked because she had the connections to people. Dot had been in it so long that people like Sharon, Ian and Martin saw her as family, to the Brannings she was family and she helped everyone and she was old as time too and with that comes wisdom and she was respected. It doesn't work with Sonia because she isn't old enough and we haven't seen her be as vulnerable as Dot. I'm not sure if the writers could ever make the audience care for Sonia the way we did for Dot, not because of Natalie Cassidy but because they haven't done any character development with her for years. Even the stuff with Rocky was glossed over because they involved Kathy in it, rather than just focus on Sonia and the Reiss storyline isn't working either.