First off, Sleigh Bells are not music for everyone--It's loud, often fuzzy (distorted) and has an edge to it--but give "Comeback Kid" or "End of the Line" a listen. If you like what you hear there, then this album is definitely for you (plus if you haven't heard the first album 'Treats' look that up as well).
If you've heard Sleigh Bells' first album 'Treats' and dug it (as I did), you will not be disappointed with 'Reign of Terror'. This is -NOT- the same album however, the sound has developed to include more emphasis on Alexis Krauss' vocals (without sacrificing Derek Miller's guitar, or the great song-writing). The sound moves from their alt/noise roots on a couple of occasions to a sort of shoegaze revisited (think "Rill Rill" off of 'Treats'--"End of the Line" here).
I think the best way I can describe 'Reign of Terror' is: it's like some modern alt/metal kids invented time travel and took over a prom in 1985.
And it's as awesome as that sounds.