I just recently got the GUILTY album from Ayu, and I am pretty impressed despite some initial hesitation. It's quite a departure from her typical trance like music; GUILTY has a predominate rock sound to it. Typically when I find myself disappointed when pop artist try rock because the things I love about rock, such as the guitar solos are avoided as to not distract attention away from the pop diva. I think the greatest example of this is during American Idol's Chris Daughtry's debut single "It's not Over" where midway through the song there seems to be a nice guitar solo, but then is cut short when he starts singing again. This kind of behavior waters down the genre in my opinion. At least Daughtry had remnants of rock, unlike many of Avril Lavigne's music, but that's another rant for another day.
There is some of the watered down feeling present in a GUILTY; although the solos aren't cut short, they aren't exactly Dream Theater or DragonForce epic solos either. But, I think what made the album work is the same thing that makes the rest of her albums work (other than the gigantic marketing engine that Avex is), her voice. The dryness of her voice that worked so well for trance music translates strangely well to "rock" music such as in "Decision". The songs are laced here and there with the typical Ayu electronic sounds. Also in typical Ayu fashion, there are a few ballads that give nice breaks in pace. Another nice touch is the use of string instruments in a few songs such as "Marionette." I've uploaded a few songs from the album into the jukebox, it's worth checking out.