Is an I1 diamond a bad diamond?

I just bought my girlfriend an engagement ring. It is not certified so I don't have the exact specifications yet. I was told it is better to get it appraised. The lady who sold it to me said it was probably an I1 clarity. Looking at it with the naked eye, however, I can't really see inclusion, if I look at it under a microscope, I can see some carbon spots. But it really looks good to the naked eye. The ring was $6,000, and the center diamond is 1 ct weight. Is an I1 diamond all that bad or should I upgrade to an SI clarity?