One aspect that feels above reproach is Morrowind's stunning graphics. The character models and environments are crammed with an astonishing level of detail, and awesome weather effects also show up from time to time, like rain and sandstorms. The first time you see a sandstorm, it'll literally take your breath away.
Morrowind will please both serious role-playing fans as well as anyone looking for a technically stunning adventure that will hold their attention longer than your average hack-and-slash title. This is the good stuff.