This is an epic album - literally (over 76 minutes) - starting with a proper pompous choral anthem and then breaking into Epica's typical hard rock music. As soon as you hear Simone Simons' vocals, you know you're in for a treat. I'm not a particular fan of 'extreme' vocals, but those of Epica's Mark Jansen fit well into the musical whole. If you've never heard of Epica before and you like hard rock with soaring female vocals and the 'big' effect of employing a choir for occasional backing, then I recommend this album without hesitation. It's not all hard rock - some ballads are filtered in (eg 'Delirium') where you can really enjoy the sound of Simone's vocals. Epica are deservedly huge in Europe and some of their earlier albums can be difficult (for that read 'expensive') to acquire (I'd guess due to conservative production volumes), but as long as you're sensible about not paying inflated prices for the rarer ones you won't be disappointed by anything you buy. From personal experience, 'The Phantom Agony', 'The Divine Conspiracy', and this are all top notch. If you can go see them live, then you must do so - some bands rely upon studio magic, but Epica are excellent.
A small plug now for the Metal Female Voices Fest (every October in Belgium) - Epica have been stalwarts of MFVF since its inception in 2003 (in their own early days) and this event has rewarded them with co-headliner status for the last few years. I've attended every year since 2007 and it's a great way to spend a weekend listening to a variety of bands (mostly European, but occasionally from further afield) spanning a range of styles from lyrical folky at one extreme to deathly at the other - something for everybody. Epica, Leaves Eyes and Delain are among the better-known regular attendees in this particular style of music, but every year I hear more good bands for the first time, so it's well worth it.