M-a says they're Symphonic Heavy Metal which I don't know whether or not to agree to it. If "Hall of the Mountain King" is an example of their original material then I would agree with this.
But, for the most part I don't know which songs are covers and which are original (other than the Metallica covers). "Repressed" sounds a lot like mid-period Sepultura and since they cover Metallica that would make them thrash, but their original stuff might be different.
And just having cellos doesn't make them symphonic or neo-classical.
@mathias: Use
http://metal-archives.com/ for genres they're a lot more reliable than wiki/myspace.