Busta Rhymes' album 'Back on My B.S.' was considered disappointing by some critics for several reasons. The album received mixed reviews, with a score of 60 out of 100 on Metacritic, indicating "mixed or average reviews". Critics pointed out issues such as subpar production quality, the overuse of autotune, and a lack of creativity in the lyrics and songwriting. The album was also criticized for its length, with some reviewers finding it overstuffed with irrelevant skits and half-baked ideas. Additionally, some tracks were seen as not living up to Busta Rhymes' usual standards, with one reviewer calling it "the worst album I've ever reviewed" on Focus Hip Hop. Furthermore, the album was viewed as a departure from Busta's earlier work, with some critics feeling that the Busta Rhymes of old was gone forever, as mentioned on Rate Your Music. While there were a few tracks that some listeners enjoyed, the overall consensus was that 'Back on My B.S.' was a disappointing effort from the artist. For more detailed reviews, you can refer to sources like Wikipedia, Focus Hip Hop, and Slant Magazine.