I confess, I'm not her biggest fan... I mean, she has a great voice, and I love the NW albums with her singing, they're great. But on stage (from what I've seen in DVDs and stuff) she could be way better, IMHO. And her solo songs are not as good as NW's songs, lets face it.
Anyway, I'm hoping that NW will come here with the next tour. (Tarja actually has a concert booked for Lisbon, but I'm not going...)