The shuffle has better quality than the mini. However, it isn't that much better that you consider the mini bad.
There are sound settings such as EQ and sound check that affect the audio quality, so see how those are set and adjust.
I/My family members have 2 shuffles, a mini, and I have a 5G iPod. They all sound close/great/similar to me. But then again, I don't have a great ear for music quality. Sounds good as long as it isn't staticky (sp?) 🙂
btabz