I have a Sky Blue Twiggy and I think it's a very pretty colour. It has faded a bit from the original colour and indoors the leather looks a different (welcome to Balenciagas - just gotta learn to love it!) blue. She is in excellent condition though and I love the smoooshy leather, she's quite distressed and just flops. It's wonderful.
I guess it depends on your wardrobe and how accomodating it is to the Sky Blue.
If you decide you don't love her, thankfully you should be able to recover most of what you spent on her.
I wish you well,
Bridget