Inclined to agree with Vix here. Rammstein is pretty damn popular, at least where I live.
As far as my opinion of them, yeah, I like 'em. Not as much as some other metal bands like Torture, but as far as newer metal goes, Rammstein and Static-X seem to have the monopoly on 'awesome'. Favorite song would have to be 'Moskau', followed up by 'Mutter'. The 'Mutter' album was one of the first albums I ever bought so it kind of has that nostalgia-blast value attached to it for me.
Mutter
Moskau