When it comes to Ali Project, I of course have to respect them for OPs they've done for Noir and Rozen Maiden season 1. Those have just become classic anime songs above reproach.
However as a band, the songs do all seem very similar. But it's not just that -- the tempo in a single song can't seem to keep the same pace, the lyrics are overblown and stupid, and the vocals are only slightly better than a car coming to a screeching stop. Why the hell is she always yelling at us in the songs now? It almost sounds like she's whining about something sometimes.
On top of that, she's always jumping around to strange, mysterious octaves that don't match the music at all. I mean have you HEARD the Avenger OP? It's like she's singing in the shower and the water keeps dramatically changing temperature.
Truthfully, though. Probably the main reason why I never watched the Shigofumi OP was because not only because it was stupid, but because the damn thing didn't fit the show -- something closer to the ED would have been better.