An amalgamation of lazy, uninspiring and uncreative writing that has poor character design, using the premise of animals to no extent for the writing or character traits whatsoever, not to mention relying on the boring premise of just jamming a bunch of pop songs people are guaranteed to know some of just to make us think we're watching something actually wholesome.
Sing is just flat out atrocious creativity wise to the animation industry, being another example of Illumination's lack of any intention to produce anything actually unique and creative and instead create films designed to simply bring in as much money as possible.
Note that I'm not forcing anyone to have the same opinion as me, feel free to enjoy this film if you wish. I just personally have a dislike to Illumination films like Sing and hope that others can agree with me as to how much of an insult these films are to anyone who appreciates the creative endeavors other companies put into making their pieces of art.