Big Sean has been on good records and made good records. He has a sense of humor, a catalog of hits, and it would be hard to say that he's unsuccessful. But he has also suffered at the hands of knee-jerk Internet hate.
It was apparent from the beginning that his relationship with Kanye benefited him greatly, helping him jump ahead of many other artists. This isn't new to hip-hop; we saw it happen with Game as well. That pedestal has made Sean a target for criticism, and his penchant for oddball ad-libs and pronunciation makes him an easy one.
As the hits have piled up, a lot of rap fans have come around to Big Sean, but he's prone to being the subject of Twitter hashtags that make fun of his lyrical approach.