Personally, I like Rozen Maiden very much and it is probably one of my お気に入り anime. The story and the plot itself is very interesting and perfectly designed. The art is good, and the characters are very well-developed as the story goes on.
Rozen Maiden released 2 seasons: "Rozen Maiden", and "Rozen Maiden; Traumend."
According to the latest news, Peach-Pit might release a new sequel to RM, intitled "Rozen Maiden Season 3."
I am very happy that Rozen Maiden will continue, it really needs a sequel because the last episode of Traumend keeps あなた attracted and makes あなた want more.
It is very sweet that Rozen Maiden is still kept in mind even though a few years have passsed, it really is a great アニメ and I am sure season 3 will come out just as good または even better than the other seasons.