Dartmouth (the UMass campus, not the Ivies) is your second-tier UMass option, located between Boston and Providence. It's smaller than Boston, more residential, and less competitive than Amherst. You're getting the UMass name for cheaper tuition in a quieter setting. Engineering and business are serviceable. The campus feels less urban-commuter than Boston, more small-town state school.
Student body is similar to Boston's—practical, regional, often first-generation. There's more residential life than Boston, which builds community, but less prestige gravity than Amherst. Graduate schools recognize the UMass degree but don't prioritize UMass-Dartmouth over the flagship.
Dartmouth works if you're choosing between it and Boston: smaller campus, still affordable, respectable academics. Skip if you're comparing to Amherst or top private schools. It's a solid middle option, not a destination.