I'm not gonna rate her looks, but playing wise; if she got a noise gate and learned to tune the guitar she'd probably be good enough to be in a 'local' metalcore band.
But you can look at this two ways:
1) She is indeed pretty good... for a giiiiirl. Although to me that is a little sexist, and patronising.
2) She is pretty poor compared to most bedroom shredding-youtube enthusiasts, of which 99.99% happen to be male. If that was a dude playing that, you'd probably be going "5/10 absolute tops"
Objectively, and honestly - compared to guys, girls are generally shit at playing metal guitar. That's not sexist, they just are. What's the point in a goddamn penis extension if you don't own a fucking penis.
If you want to disagree then tell me your favourite and most influential 100 guitar players.
(having said all that my wife is pretty sweet at guitar hero and can complete most of the songs on 'hard' after only owning it for 2 or 3 weeks. Although I know GH isn't exactly like playing a real instrument...)