A good financial aid package would be significant scholarship money/tuition waiver/grant/whatever that decreases your loan burden by a significant amount.
Nearly any US citizen applicants will qualify for 100% of the estimated annual costs in loans, even if you and/or your family have significant assets. That’s a bad aid package as it’s really no aid at all.
But your 100% loan aid letter will begin with, “Congratulations, ...”
What’s good? 30%, 50%?
Great would be anything that approached 100% of the estimated costs of attendance.