Well, let's have a glimpse at the band's biography; it hails from Finland and is female fronted. Actually, the lady who sings for AMBERIAN DAWN has a classical music education and a soprano voice. I think this information is more than enough for everyone to guess the musical whereabouts of this sextet from the northern Europe; symphonic Metal in the vein of the early NIGHTWISH with albums like Angels Fall First or Oceanborn.
AMBERIAN DAWN was formed after the disband of VIRTUOCITY who started working on songs composed by Tuomas Seppala. The lineup took the today's form in the summer of 2006 when  Heidi Parviainen bringing in the opera vocals.
One thing that you notice when River Of Tuoni kicks in is that the band's sound is way too much like NIGHTWISH! One difference that is not that noticeable is that the music is based more on the guitars and less on the keyboards giving the songs a straightforward attitude. Indeed, you won't find here pompous orchestrations or complicated melodies. AMBERIAN DAWN keep it simple and from my point of view they spoil the entire atmosphere. I mean if you are going to play Symphonic Metal you have to make it pompous! Although  Heidi;s voice will photograph Tarjia she has a softer and a warmer voice the kind of spice things up a little bit..
As I said the song structure is kept simple making the song sound weak and incomplete. This doesn't mean River Of Tuoni is a bad album, not at all; the band has potentials as heard in songs like Fate Of The Maiden or Sunrise with the nice  guitar driven melodies.
So, if something that I said above sounds a little bit interesting for you then you can visit the band's myspace page and have a close look. As for me, I'll pass...