I think it looks great. True the back isn't as angled as Posh's, but I think it looks great. I say give the salon a call and explain to them you aren't really happy and would like to go back in in a few days, that way you can have a few days to adjust to everything and they know what's up.
PS- totally taking a picture of your hair to my stylists because I love your highlights. They're exactly what I've been wanting but I have such a hard time explaining it!