There are a few things that Era 1 does arguably better than most of Brandon's works, IMO.

For one thing The Final Empire is very good at being a self-contained book.

Another good point is Vin's characterization is done really well through some show-not-tell cues, like her continuing to hoard food, or her dumb assumptions that Kelsier is withholding information to control her or whatever. The reader learns about Vin's mental state just by being an objective observer of her behavior, unlike some other Cosmere characters where the reader is constantly told, "hey, this person is sad", etc.

She's very well written IMO, and characters like Kaladin are certainly more developed as Brandon has grown as a writer, but I think there are parts of Final Empire where the gradual introduction of Vin's mental state remains Brandon's best work to me.