They are almost unbelievably fun live. Sheer, audacious showmanship. Their music is ok, especially Mutter, which was the first CD I ever bought not duplicated in my parents record or cassette collections, but it's really just a re-hash of Oomph!* and Laibach. I've got bored of it now. But the stage show! Fuck yes! Rammstein supported by Apocalyptica is still one of the all time best live events, let alone gigs, I have ever seen. Flamethrowers, explosions, sodomy, leashes, rubber dinghies, stormtrooper helmets, meat cleavers and fuck knows what else. Perfect leather club music.
*Though they're better than Oomph! to my mind.