Tarja's solo albums have great songs on them, but they aren't much to talk about as whole albums.
I'm with bosk1 and jingle.boy. As much as I like Annette, Tarja gave Nightwish that extra notch above so many other bands, and Tarja just lacks something going solo. Her singing is fine, her songs are all over the place. I still think Nightwish is really good, but... oh well.