I guess this is as good as the sound quality will get from an ani-song singer. It's certainly many orders of magnitude better than CDs most companies are stamping out these days, but it's far from audiophile quality. But then, we're talking pop music. I think I can accept this level of sound quality, if it's maintained (or improved!).
This time, most, if not all, of the songs appear to be recorded and mastered using higher than usual sampling rate (better than 48kHz), except maybe tracks 5 and 7, but those might be due to synthesizer limitations, not recording limitations.
If you look at the SACD vs. CD waveforms, you'll notice CD version is always more dynamically compressed, but the rate is extremely consistent. Even the CD side is not as badly compressed compared to most other CDs these days, so it's not such a bad buy even if you don't have an SACD player, but if you do, you should opt for the SACD layer. Note, if you get confused on which one is which, just look at the sampling rate. If it's 44100, it's CD. If it's 96000, it's SACD (that is the limit of my old M-Audio soundcard).
As for the music, I'm actually not all that fond of where she's been heading. She used to have deeper and darker (not necessarily negative) songs that resonate with power, but too many of her songs these days are light and, well, kind of boring.
My favorite on this CD are track 4 and 12.
Update: 2010-01-14: Actually, I partially take back the negative comment about the music. After attending her live (both days 2010-01-02/03), which was set up for spectacular sound quality, I now believe the problem is mostly sound quality. Track 12, for example, would have far more impact if it had more dynamics and proper frequency coverage. It's so bad, I'm downgrading this to 4-stars. And this an SACD, too. What a sad state of affairs.
