First off, I am a huge sucker for chiks doing metal. That said, I think the female voices are beautiful. But though I can't truly say that they are uninspired I've definately heard better bands using this formula.
So as for musical appeal I'd much rather listen to Nightwish, they have more edge. And as for the whole theme thing I'd much rather listen to Blind Guardian.
Though "Sons of Riddermark" is damned catchy sometimes.
talking about female voices, arch enemy's now female voice Angela Gossow has quite an original voice, to not say inspired ^^
Anglorfin if ur a sucker for chicks doing metal i'm sure you know how fine she is
but i can't say her voice is beautiful har har