I think facially she's above-average (if by above-average we mean girls who don't have an odd feature like a too long nose or bad teeth or bad skin) but overall she's really attractive and super, super hot. She's sensual, and that's something which isn't very easily pulled off. I mean, many think being sexy is all about wearing certain clothes or having a certain hair colour, but as often as not it's innate.
Amber's 'got it' like how Kate Beckinsale has got it, whilst prettier girls than her like Blake Lively struggle to look effortlessly ultra sexy.