I think I'll just quote myself from what I posted on Josh's blog.
I got [Rosenrot] the other day and yes, it is AMAZING!
I actually think they underwent [a] metamorphosis with Reise, Reise. With that album they really reached a whole new level. Their sound became very mature, and their lyrics became a lot more serious (Compare “Tier” and “Bück dich” from Sehnsucht to “Morgenstern” and “Stein um Stein” from Reise, Reise). Which is not to say they are no longer the naughty little tongue-in-cheek boys they once were, but their cheekiness comes out in more subtle ways, a line here, a note there. And of course, through their signature Rammstein “twist at the end.”
I think the Rosenrot album as a whole is a lot like its liner art: introverted, and with a bit of a goth-cabaret feeling going on. It carries on with the seriousness of Reise, Reise but also has several moments of youthful frivolousness.
I am completely in love with [the songs] “Mann gegen Mann” (Which is a rather cheeky song) and “Rosenrot.” The only disappointment was “Ein Leid” which I feel would have worked better as a fast, hard-hitting song.
And now I have to go listen to the album again.