I have to agree with what you both have to say, Lise and Kat. It's a real shame that Leah is a underutilised character, Ada has shown us in the past what she can do.Maybe she will get a good storyline after the series finale events, mind you I would have liked to see the Bridget and Leah storyline go in a slightly different way that it has.
Leah and Rachels friendship is really great, hopefully Rachel's pregnancy (and becoming a parent)might even bring them closer by being able to talk about their own experiences, etc.Mind you, the friendship she had with Sal was great too.
My only disappointment is there is certainly items of her wardrobe that have been overused and should be burnt, not to mention a certain tunic (which I can't stand her wearing).