As good as or better, but definitely not worse. Most files played from a CD in your computer are at 96 to 128Kbps. All of mine in my iPod are at 160 or 192Kbps. You will hear that difference quickly.
You can rip your CDs for that bitrate, and the iPod will play it just like that. Sometimes, however, ripping a CD at a higher bitrate won't make a bit of difference, especially with older CDs.
But I gather that there's some compression in the storage/playback chain somewhere -- and my impression is that it's always "on" in an iPod. The compression can't be gotten around.
I'm guessing that even though the original file may have been recorded at a higher bit rate, the compressed version that gets stored on the iPod isn't at that high of a bit rate.
But I could be completely wrong on this.